Method, System, and Computer Program Product for the Detection of Physical Activity by Changes in Heart Rate, Assessment of Fast Changing Metabolic States, and Applications of Closed and Open Control Loop in Diabetes

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First Claim
1. A method for detecting physical activity and its effects on metabolic demand, said method comprising:
 detecting onset of the physical activity using changes in heart rate data.
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Abstract
A method, system, and computer program product related to the detection of physical activity using changes in heart rate. The method, system, and computer program product evaluates short term glucose demand and long term insulin action due to physical activity. The method, system, and computer program product is further related to the improvement of open and closed loop control of diabetes by accounting for the metabolic changes due to physical activity. The method, system, and computer program product is directed to detecting in real time the short and long term effects of physical activity on insulin action via heart rate analysis, and recommending changes in insulin dosing to compensate for the effects of physical activity. With these recommendations, the open and closed loop control of diabetes can be improved and steps can be taken to prevent hypoglycemia that may result from increased insulin sensitivity due to physical activity.
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261 Claims
 1. A method for detecting physical activity and its effects on metabolic demand, said method comprising:
 detecting onset of the physical activity using changes in heart rate data.
 View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87)
 88. A system for detecting physical activity and its effects on metabolic demand, said system comprising:
 a processor programmed to detect onset of the physical activity using changes in heart rate data.
 View Dependent Claims (89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174)
 175. A computer program product comprising a computer useable medium having computer program logic for enabling at least one processor in a computer system to detect physical activity and its effects on metabolic demand, said computer program logic comprising:
 detecting onset of the physical activity using changes in heart rate data.
 View Dependent Claims (176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261)
1 Specification
The present application claims priority from U.S. Provisional Application Ser. No. 60/861,217, filed Nov. 27, 2006, entitled “Method, System, and Computer Program Product for Closedloop Control in Diabetes During Fast Changing Metabolic States Reflected by Changes in Heart Rate,” U.S. Provisional Application Ser. No. 60/919,103, filed Mar. 20, 2007, entitled “Method, System, and Computer Program Product for Closedloop Control in Diabetes During Fast Changing Metabolic States Reflected by Changes in Heart Rate,” and U.S. Provisional Application Ser. No. 60/982,251, filed Oct. 24, 2007, entitled “Method, System, and Computer Program Product for Closedloop Control in Diabetes During Fast Changing Metabolic States Reflected by Changes in Heart Rate,” the entire disclosures of which are hereby incorporated by reference herein in their entirety.
GOVERNMENT SUPPORTWork described herein was supported by Federal Grant No.RO1 DK 51562, awarded by National Institutes of Health. The United States Government has certain rights in the invention.
FIELD OF INVENTIONThe present system relates generally to the art of open and closed loop control systems for the control of diabetes, and more importantly to the assessment of changes in insulin sensitivity.
BACKGROUND OF THE INVENTIONRecent advancements in diabetes technology include two parallel rapidly evolving areas: insulin delivery devices (subcutaneous or implanted insulin pumps) and continuous glucose monitors (CGM) recording frequent glucose determinations. So far, these two types of devices have not been linked successfully in a closedloop glucose control system, e.g. artificial pancreas, which has the potential to dramatically improve blood glucose (BG) control, advance the quality of diabetes care, and help prevent costly complications of diabetes. Arguably, a minimallyinvasive subcutaneous, SCSC closed loop would have greatest potential for everyday use. Currently, there are five available SC CGM devices and several SC insulin pumps. A major challenge to a reliable external closedloop control based on CGM and SC insulin injection remains the development of optimal control algorithms. A major obstacle to optimal control are two time delays inherent with SC systems: (i) the CGM resides in interstitial fluid and there exists a 520 minute time lag due to bloodtointerstitial glucose transport and sensor limits, and (ii) a change in the rate of insulin delivery takes ˜30 minutes to result in change in insulin action. While these time delays have little impact in steady metabolic states (e.g. during sleep), they are critical during rapidly changing metabolic demands, such as meals and physical activity.
Physical activity is recognized as a major trigger of potentially dangerous hypoglycemia. While patients may ingest glucose to compensate for acutely higher demand during exercise, the longterm (several hours) increase in insulin sensitivity attributed to exercise typically remains hidden. In addition, in automated closed loop, both the acute and longterm effects of physical activity will need to be handled without assistance. However, physical activity cannot be reliably detected via glucose monitoring alone because counterregulatory and other processes delay the BG fall. As a result, in most instances, a control algorithm relying on CGM data alone, would fail to reduce the insulin infusion in a timely way and would risk inducing hypoglycemia.
An additional input beyond BG is needed to detect the onset and magnitude of physical activity. A logical candidate for such a data input is heart rate (HR). Thus, the technology proposed regarding various aspects of the present invention meets an important need and provides the capability to overcome a major obstacle to closedloop control—the inability to account for metabolic changes due to physical activity—by providing an additional information source through HR analysis.
During the past 10 years we have developed an array of mathematical methods describing the pathophysiology of Type 1 and Type 2 diabetes (T1DM, T2DM) at several system levels, from glucoseinsulin control network to selftreatment behavior. Recently we have established collaboration with Prof. Claudio Cobelli, University of Padova, Italy, who has longstanding high visibility in the field of modeling glucose dynamics and is one of the authors of the now classic Glucose Minimal Model of Glucose Kinetics (MMGK).
Aspects associated with various embodiments of the present invention achieves, but not limited thereto, the following method, system and computer program product having the following objective: quantitatively describe the effects of physical activity on glucoseinsulin dynamics in T1DM and develop an algorithm detecting via heart rate analysis the shortterm and longterm changes in insulin sensitivity resulting from exercise. The method, system and computer program product may utilize the proposed algorithm that would have applications in both openloop control systems providing feedback about metabolic state to the patient, and in fully automated closedloop artificial pancreas.
Insulin SensitivityThe dynamics of interstitial concentrations of insulin and glucose has been mathematically characterized by Bergman and Cobelli's now classic MMGK [2],[3], and in a number of subsequent studies [4][10]. As a result, excellent methods exist for quantitative assessment of insulin sensitivity in a laboratory [4] and in an outpatient setting from oral glucose tolerance test (OGTT) [7]. The MMGK allows estimation of insulin sensitivity (SI) and insulin action (X) from intravenous tests (FIG. 1). Dr. Cobelli's group has been at the forefront of these investigations, with more than 200 publications addressing various aspects of glucoseinsulin dynamics in health and disease, including estimates of postprandial glucose dynamics [13][17]. Usually the model is numerically identified by nonlinear least squares or maximum likelihood methods, however more sophisticated approaches in healthy and T2DM subjects have been used as well [19],[20]. The potential for adding a glucose tracer allowing the segregation of insulin action on periphery vs. the liver, has been investigated as well [20].
The MMGK is designed to mimic physiology via two ordinary differential equations: one governing the dynamics of glucose (considered to be a unique compartment G), another governing the dynamics of remote insulin action (compartment X). In these equations (presented below) S<sub>G </sub>represents the balance between liver production/clearance and insulin independent utilization, linearized around a basal glucose value G<sub>b</sub>; X represents the insulin dependent glucose clearance; and Ra(t) the external input of glucose (meal or IV injection). The insulin dependent clearance is also a linear simplification around the basal insulin level I<sub>b</sub>, and insulin sensitivity is defined as gain of the second equation:
<maths id="MATHUS00001" num="00001"><math overflow="scroll"><mrow><msub><mi>S</mi><mi>I</mi></msub><mo>=</mo><mrow><mfrac><msub><mi>p</mi><mn>3</mn></msub><msub><mi>p</mi><mn>2</mn></msub></mfrac><mo>.</mo></mrow></mrow></math></maths>
<maths id="MATHUS00002" num="00002"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>{</mo><mtable><mtr><mtd><mrow><mover><mi>G</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mo></mo><mrow><msub><mi>S</mi><mi>G</mi></msub><mo></mo><mrow><mo>(</mo><mrow><mi>G</mi><mo></mo><msub><mi>G</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow><mo></mo><mrow><mi>X</mi><mo>·</mo><mi>G</mi></mrow><mo>+</mo><mfrac><mrow><mi>Ra</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mi>V</mi></mfrac></mrow></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>X</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><msub><mi>p</mi><mn>2</mn></msub></mrow><mo></mo><mi>X</mi></mrow><mo>+</mo><mrow><msub><mi>p</mi><mn>3</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>I</mi><mo></mo><msub><mi>I</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd></mtr></mtable></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>1.1</mn></mrow></mtd></mtr></mtable></math></maths>
Effect of exercise on glucose homeostasis: Optimal meal management requires the injection, in a timely fashion, of enough insulin to return to target blood glucose value within minimum time, avoiding hypoglycemia. The challenge with physical activity is different in that we are not reacting to a system perturbation (such as glucose entering the blood via the GI track) but to transient changes in the parameters of glucose/insulin dynamics, which lead to increased effectiveness of insulin [21], and potentially to hypoglycemia. These changes are well known, though not always precisely quantified, and revolve mostly around changes in glucose transport through the cell membrane and vascular changes (FIG. 2). Exercise has been shown to augment the availability of the glucose transporter GLUT4, both by translocation to the cell membrane [22][24] and increased transcription in muscle cells [25],[26]. These changes have been shown to be associated with an increase in insulin sensitivity and insulin independent glucose uptake [21],[24],[27],[28]. The pathways of exerciseinduced translocation and augmented transcription are not entirely elucidated yet; but muscle fibers contractions have been proven to be at the source of these changes [28]. Though abundantly studied, the effects of exercise on glucose/insulin dynamics have been primarily approached in medical and biological terms. Concepts such as glucose transporter translocation, insulin sensitivity increase, or changes in transcription of transporters have been shown but never with a quantitative approach in mind. It is not to say that models have not been used to study these phenomena—there are numerous examples in the literature of studies using different versions of the MMGK to compare the glucose dynamics pre and post exercise [21],[27],[29][33]. However, realtime detection of the short and longterm effects of physical activity on insulin sensitivity has not been accomplished.
Heart rate is a natural marker of physical activity due to its availability in the field and strong link with exercise duration and intensity [37]. Other metrics could be better suited to measure exercise intensity (e.g. V<sub>O2max </sub>and lactate threshold) and are tightly related to qualitative change in exercise physiology [38], but they are difficult to measure in field conditions. Considering the strong linear relationship displayed between maximum heart rate and V<sub>O2max </sub>[39], the proposed invention uses the difference between HR and a basal measure (minimum HR at rest) as a marker of exercise.
SUMMARY OF THE INVENTIONClosed loop systems have been proven difficult to apply in clinical diabetes management, for both technical and physiological reasons. The automatic injection of insulin in patients with Type 1 diabetes (T1DM), a timely and adapted response to changing blood glucose levels, is naturally impaired by erroneous, or delayed, blood glucose reading, and technological delays in exogenous insulin action. For these reasons, simple modelindependent control algorithms, such as PID controllers, have insofar failed to provide reliable, safe, automatic control of T1DM. Though more promising and more complex, modelpredictive control (MPC) algorithms are still in development phase and are unable to tackle major daily life challenges, such as meals and physical activity. One of the reasons these algorithms (both PID and MPC) fail to provide a robust closed loop system is the inconsistent nature of the physiological reaction to insulin. This reaction is quantified by the well known index Insulin Sensitivity (SI), derived from the BergmanCobelli minimal model of glucose kinetics. The problem is that the SI changes rapidly with any system disturbance and many such changes are hard to detect via glucose monitoring alone. Certain changes in glucose utilization and insulin action due to meals are well modeled; the circadian rhythm of the SI is understood as well. However, the effect of physical activity, and more importantly its quantifying, is largely unknown. An aspect of various embodiments of the present invention method, system and computer program product to be included in open and closedloop systems may comprise, but not limited thereto, the following:
 The addition of heart rate (HR) monitoring;
 * The detection of physical activity, its duration and intensity, through HR and glucose changes;
 The modeling of changes in glucose uptake due to physical activity, in potentially two phases:
 A shortterm phase corresponding to increased glucose utilization during physical activity and shortly (12 hours) after;
 A longterm phase (hourstodays) corresponding to changes in insulin sensitivity and glucose replenishment triggered by prolonged intense physical activity;
 The computing of recommended changes in insulin dose compensating for the effects of physical activity on insulin sensitivity.
In summary, an aspect of various embodiments of the present invention method, system and computer program product may focus on, but not limited thereto, the changes in glucose/insulin dynamics in T1DM during and after exercise and their quantification via mathematical modeling. Once identified and quantified these dynamics can be used to adapt insulin delivery to announced, or detected via heart rate, amount of exercise and therefore avoid under and overestimation of insulin needs. Such an optimal treatment would minimize the frequency of hypo and hyperglycemic episodes frequently following over or under compensation for exercise, would be applicable to openloop control treatment strategies (e.g. adaptive basal insulin and bolus patterns), and would be particularly critical in any closedloop application relying on automated insulin delivery.
An aspect of an embodiment of the present invention provides a method (and related system and computer program product) for detecting physical activity and its effects on metabolic demand. The method (and related system and computer program product) may further comprise: detecting onset of the physical activity using changes in heart rate data. The method may further comprise acquiring heart rate data. Further, the detection of physical activity may comprise: transforming the heart rate data; computing an index to detect physical activity based on results of the transformation; and detecting physical activity using the index and the heart rate data.
An aspect of an embodiment of the present invention provides a method (and related system and computer program product) for detecting physical activity and its effects on metabolic demand. The method (and related system and computer program product) may further comprise: evaluating effects of physical activity on glucose demand. The method may further comprise: acquiring glucose data and heart rate data. Further, the detection of physical activity may comprise: transforming the heart rate data; computing an index to detect physical activity based on results of the transformation; and detecting physical activity using the index and the heart rate data.
An aspect of an embodiment of the present invention provides a method (and related system and computer program product) for detecting physical activity and its effects on metabolic demand. The method (and related system and computer program product) may further comprise: evaluating changes in insulin sensitivity and glucose demand due to the physical activity; and indicating recommendations of insulin dosing. The method may further comprise: acquiring glucose data, insulin delivery data and heart rate data. Further, the detection of physical activity may comprise: transforming the heart rate data; computing an index to detect physical activity based on results of the transformation; and detecting physical activity using the index and the heart rate data.
A method, system, and computer program product related to the detection of physical activity using changes in heart rate. The method, system, and computer program product evaluates short term glucose demand and long term insulin action due to physical activity. The method, system, and computer program product is further related to the improvement of open and closed loop control of diabetes by accounting for the metabolic changes due to physical activity. The method, system, and computer program product is directed to detecting in real time the short and long term effects of physical activity on insulin action via heart rate analysis, and recommending changes in insulin dosing to compensate for the effects of physical activity. With these recommendations, the open and closed loop control of diabetes can be improved and steps can be taken to prevent hypoglycemia that may result from increased insulin sensitivity due to physical activity.
These and other objects, along with advantages and features of the invention disclosed herein, will be made more apparent from the description, drawings and claims that follow.
BRIEF SUMMARY OF THE DRAWINGSThe accompanying drawings, which are incorporated into and form a part of the instant specification, illustrate several aspects and embodiments of the present invention and, together with the description herein, and serve to explain the principles of the invention. The drawings are provided only for the purpose of illustrating select embodiments of the invention and are not to be construed as limiting the invention.
FIG. 1 provides a graphical representation of the Minimal Model of Glucose Kinetics.
FIG. 2 provides a graphical representation of the effect of exercise on transmembrane glucose transport.
FIG. 3 provides a graphical representation of the Exercise Minimal Model of Glucose Kinetics (EMMGK).
FIG. 4 provides a graphical representation of the model of insulin kinetics.
FIG. 5 provides a graphical representation of the validation of spectral index detection of exercise.
FIGS. 6(A)(C) provide a graphical representation of the case study of changes in glucose usage due to exercise. Case study: day1 of subject 121, referring to FIG. 6(A): glucose measure (as illustrated by red crossmarks “+” having a line there through it), injection (as illustrated in blue crossmarks “+”) and modeling (blue curve); FIG. 6(B): insulin injection (blue, as identified as “insulin pump” in the graph), concentration (green as identified as “free insulin” in the graph) and action (black as identified as “remote insulin action” in the graph); FIG. 6(C): transient (blue as identified as “glucose pump” in the graph) and long term (red as identified as “Si” in the graph) changes in glucose usage.
FIG. 7 provides a graphical representation of the average increase in insulin action due to exercise, illustrated by the shaded area representing the average difference between the theoretical (MMGK) and empirical insulin action.
FIG. 8 provides a comparison of the classic MMGK and the new Exercisespecific model, illustrating the superiority of the EMMGK according to the Akaike information criterion. The MMGK is graphically illustrated with the bar graphs having lighter shading and the EMMGK is graphically illustrated with the bar graphs having darker shading
FIG. 9 provides a graphical representation of sharp increase in glucose consumption and change in insulin secretion due to exercise. Measured samples are represented by blue as illustrated by cross marks “+” and smoothed curved are in red as illustrated by solid lines.
FIG. 10 provides a block diagrammatic representation of one of the embodiments of the invention.
FIG. 11 provides a functional block diagram (an exemplary and nonlimiting example) for a computer system for implementation of embodiments of the present invention.
FIG. 12 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for detecting physical activity, its duration and intensity through HR.
FIG. 13 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for quantifying shortterm and/or longterm changes in insulin sensitivity due to physical activity.
FIG. 14 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for computing recommended changes in insulin dose to compensate for the effects of physical activity on insulin sensitivity
DETAILED DESCRIPTION OF THE INVENTIONAn aspect of various embodiments of the present invention method, system and computer program product comprises, but not limited thereto, the quantitative estimation of shortterm and longterm changes in individual insulin sensitivity (SI) from heart rate. The computation of these changes may rely on the mathematical algorithm described below, which is derived from the classic MMGK. As shown in the literature, the parameters of the minimal model (S<sub>I </sub>but also S<sub>G </sub>) can significantly change during and after physical activity [21],[34]. These changes are consequence from vascular and metabolic adaptations to increased energy utilization and storage described above, rendering the minimal model impossible to use during exercise without a precise description of the amplitude and dynamics of these changes. Moreover, without announcement, the timing of exercise is not known, making difficult any realtime exercise detection.
The Exercise Minimal Model of Glucose KineticsIn a previous publication [36] we have shown that changes in glucose/insulin dynamics due to mild to moderate exercise can be described in two phases: a transient change in insulin independent glucose clearance and a longer term change in insulin sensitivity, confirming and expanding the work of Derouich et al. [34] with clinical data. The EMMGK is a model based on these studies but with no changes in model parameters. Instead we minimally augment the state of the system, using HR as a driving function. This results in the augmentation of MMGK (See FIG. 1) with two additional compartments Y and Z presented in FIG. 3.
The equations governing these compartments are:
<maths id="MATHUS00003" num="00003"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>{</mo><mrow><mrow><mtable><mtr><mtd><mrow><mover><mi>G</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mo></mo><mrow><msub><mi>p</mi><mn>1</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>G</mi><mo></mo><msub><mi>G</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Y</mi></mrow></mrow><mo>)</mo></mrow><mo></mo><mrow><mi>X</mi><mo>·</mo><mi>G</mi></mrow></mrow><mo>+</mo><mfrac><mi>D</mi><msub><mi>V</mi><mi>g</mi></msub></mfrac></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>X</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><msub><mi>p</mi><mn>2</mn></msub></mrow><mo></mo><mi>X</mi></mrow><mo>+</mo><mrow><msub><mi>p</mi><mn>3</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>I</mi><mo></mo><msub><mi>I</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>Y</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac></mrow><mo></mo><mi>Y</mi></mrow><mo>+</mo><mrow><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac><mo></mo><mrow><mo>(</mo><mrow><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow><mo></mo><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>Z</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><mrow><mo>(</mo><mrow><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow><mo>+</mo><mfrac><mn>1</mn><mi>τ</mi></mfrac></mrow><mo>)</mo></mrow></mrow><mo>·</mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mtd></mtr></mtable><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mi>where</mi><mo></mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mfrac><msup><mrow><mo>(</mo><mfrac><mi>Y</mi><mrow><mrow><mi>a</mi><mo>·</mo><mi>H</mi></mrow><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mfrac><mo>)</mo></mrow><mi>n</mi></msup><mrow><mn>1</mn><mo>+</mo><msup><mrow><mo>(</mo><mfrac><mi>Y</mi><mrow><mrow><mi>a</mi><mo>·</mo><mi>H</mi></mrow><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mfrac><mo>)</mo></mrow><mi>n</mi></msup></mrow></mfrac></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>1.2</mn></mrow></mtd></mtr></mtable></math></maths>
In the first equation glucose clearance is augmented during exercise via both the insulin independent (by αY) and insulin dependent terms (by βZ). Y is computed as ΔHR smoothed and delayed via a first order linear ordinary differential equation (ODE). Thus, Y represents the transient shortterm increase in glucose uptake due to exercise. Z is controlled via a non linear ODE driven by f(Y). The function f(Y) is constructed so that it is negligible until Y reaches a certain fraction of the basal HR, corresponding to onset of exercise; f(Y) reaches 1 rapidly thereafter (speed is dependent on a and n) and drives Z upward. After exercise f(Y) resumes a negligible value, allowing Z to slowly drift back via quasi exponential decay driven by τ. Thus, Z represents the longterm change in insulin sensitivity due to exercise. It should be appreciated that alternative solutions of the aforementioned equation may be implemented to achieve the objective of the present invention.
Short Term EquationThe equation below corresponds to short term changes in glucose demand and short term changes in glucose demand and insulin action:
<maths id="MATHUS00004" num="00004"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>{</mo><mtable><mtr><mtd><mrow><mover><mi>G</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mo></mo><mrow><msub><mi>p</mi><mn>1</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>G</mi><mo></mo><msub><mi>G</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><mn>1</mn><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Y</mi></mrow></mrow><mo>)</mo></mrow><mo></mo><mrow><mi>X</mi><mo>·</mo><mi>G</mi></mrow></mrow><mo>+</mo><mfrac><mi>D</mi><msub><mi>V</mi><mi>g</mi></msub></mfrac></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>X</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><msub><mi>p</mi><mn>2</mn></msub></mrow><mo></mo><mi>X</mi></mrow><mo>+</mo><mrow><msub><mi>p</mi><mn>3</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>I</mi><mo></mo><msub><mi>I</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>Y</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac></mrow><mo></mo><mi>Y</mi></mrow><mo>+</mo><mrow><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac><mo></mo><mrow><mo>(</mo><mrow><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow><mo></mo><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mtd></mtr></mtable></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>1.3</mn></mrow></mtd></mtr></mtable></math></maths>
where G represents glucose value, G<sub>b </sub>is basal glucose value, X is insulin dependent action, D represents glucose input, V is the diffusion volume, I is the insulin value, I<sub>b </sub>represents basal insulin value, Y represents the transient variation in metabolic activity, β represents the short term metabolic demand to heart rate ratio, HR represents heart rate, HR<sub>b </sub>represents basal heart rate, p<sub>1 </sub>represents the balance between liver production/demand and insulin independent glucose demand, τ<sub>HR </sub>represents the lag between onset of physical activity and changes in metabolic demand, p<sub>2 </sub>represents the lag between appearance of insulin and action of insulin, and p<sub>3 </sub>represents the intensity of insulin action. It should be appreciated that alternative solutions of the aforementioned equation may be implemented to achieve the objective of the present invention.
Long Term EquationThe equation below corresponds to long term changes in glucose demand and long term changes in glucose demand and insulin action:
<maths id="MATHUS00005" num="00005"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>{</mo><mrow><mrow><mtable><mtr><mtd><mrow><mover><mi>G</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mo></mo><mrow><msub><mi>p</mi><mn>1</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>G</mi><mo></mo><msub><mi>G</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Z</mi></mrow></mrow><mo>)</mo></mrow><mo></mo><mrow><mi>X</mi><mo>·</mo><mi>G</mi></mrow></mrow><mo>+</mo><mfrac><mi>D</mi><msub><mi>V</mi><mi>g</mi></msub></mfrac></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>X</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><msub><mi>p</mi><mn>2</mn></msub></mrow><mo></mo><mi>X</mi></mrow><mo>+</mo><mrow><msub><mi>p</mi><mn>3</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>I</mi><mo></mo><msub><mi>I</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>Y</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac></mrow><mo></mo><mi>Y</mi></mrow><mo>+</mo><mrow><mfrac><mn>1</mn><msub><mi>τ</mi><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow></msub></mfrac><mo></mo><mrow><mo>(</mo><mrow><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>R</mi></mrow><mo></mo><mrow><mi>H</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mover><mi>Z</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mrow><mo></mo><mrow><mo>(</mo><mrow><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow><mo>+</mo><mfrac><mn>1</mn><mi>τ</mi></mfrac></mrow><mo>)</mo></mrow></mrow><mo>·</mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mtd></mtr></mtable><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mi>where</mi><mo></mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mrow><mi>f</mi><mo></mo><mrow><mo>(</mo><mi>Y</mi><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mfrac><msup><mrow><mo>(</mo><mfrac><mi>Y</mi><mrow><mrow><mi>a</mi><mo>·</mo><mi>H</mi></mrow><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mfrac><mo>)</mo></mrow><mi>n</mi></msup><mrow><mn>1</mn><mo>+</mo><msup><mrow><mo>(</mo><mfrac><mi>Y</mi><mrow><mrow><mi>a</mi><mo>·</mo><mi>H</mi></mrow><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><msub><mi>R</mi><mi>b</mi></msub></mrow></mfrac><mo>)</mo></mrow><mi>n</mi></msup></mrow></mfrac></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>1.4</mn></mrow></mtd></mtr></mtable></math></maths>
where G represents glucose value, G<sub>b </sub>is basal glucose value, X is insulin dependent action, D represents glucose input, V is the diffusion volume, I is the insulin value, I<sub>b </sub>represents basal insulin value, Y represents the transient variation in metabolic activity, β represents the short term metabolic demand to heart rate ratio, Z represents the longterm change in insulin sensitivity due to physical activity, α represents the long term change amplitude, HR represents heart rate, HR<sub>b </sub>represents basal heart rate, p<sub>1 </sub>represents the balance between liver production/demand and insulin independent glucose demand, τ<sub>HR </sub>represents the lag between onset of physical activity and changes in metabolic demand, p<sub>2 </sub>represents the lag between appearance of insulin and action of insulin, p<sub>3 </sub>represents the intensity of insulin action, α represents the fraction of basal heart rate above basal heart rate at which physical activity is detected, and n represents the steepness of the aforementioned threshold.
Identifying the EMMGKThe described model is highly subjectspecific: S<sub>I </sub>but also S<sub>G </sub>or p<sub>2 </sub>can have up to 10fold difference between people; therefore identifying the model parameters for a particular person critical is critical for its algorithmic application. To estimate the model parameters we first assume that blood glucose, blood insulin, and heart rate are available. In this case, we fix τ, τ<sub>EX</sub>, α, and n to reflect published results (e.g. significant S<sub>I </sub>augmentation for up to 20 hours after exercise). Then, by recursively differentiating the model we can demonstrate that, if plasma glucose, insulin, and HR are measured, all non fixed parameters are theoretically identifiable.
Insulin KineticsIn practice, insulin concentration is difficult to measure and is impossible to measure under field conditions. Thus, we derive insulin concentration from the only available source of insulin data in T1DM—the rate of insulin infusion from the insulin pump. This extrapolation requires knowledge of the kinetics of insulin transport from subcutaneous delivery (insulin pump) to blood. Insulin kinetics can be modeled via the 2compartment model in FIG. 4. This model was first presented by Dalla Man [45] in T2DM and health and further refined in T1DM.
The model equations are:
<maths id="MATHUS00006" num="00006"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>{</mo><mrow><mrow><mtable><mtr><mtd><mrow><msub><mover><mi>I</mi><mo>.</mo></mover><mi>P</mi></msub><mo>=</mo><mrow><mrow><msub><mi>m</mi><mn>1</mn></msub><mo></mo><msub><mi>I</mi><mi>L</mi></msub></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><msub><mi>m</mi><mn>2</mn></msub><mo>+</mo><msub><mi>m</mi><mn>4</mn></msub></mrow><mo>)</mo></mrow><mo></mo><msub><mi>I</mi><mi>P</mi></msub></mrow><mo>+</mo><mrow><msub><mi>k</mi><mn>1</mn></msub><mo></mo><msub><mi>I</mi><msub><mi>SC</mi><mn>1</mn></msub></msub></mrow><mo>+</mo><mrow><msub><mi>k</mi><mn>2</mn></msub><mo></mo><msub><mi>I</mi><msub><mi>SC</mi><mn>2</mn></msub></msub></mrow></mrow></mrow></mtd></mtr><mtr><mtd><mrow><msub><mover><mi>I</mi><mo>.</mo></mover><mi>L</mi></msub><mo>=</mo><mrow><mrow><msub><mi>m</mi><mn>2</mn></msub><mo></mo><msub><mi>I</mi><mi>P</mi></msub></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><msub><mi>m</mi><mn>1</mn></msub><mo>+</mo><msub><mi>m</mi><mn>3</mn></msub></mrow><mo>)</mo></mrow><mo></mo><msub><mi>I</mi><mi>L</mi></msub></mrow></mrow></mrow></mtd></mtr><mtr><mtd><mrow><msub><mover><mi>I</mi><mo>.</mo></mover><msub><mi>SC</mi><mn>1</mn></msub></msub><mo>=</mo><mrow><mrow><mrow><mo></mo><mrow><mo>(</mo><mrow><msub><mi>k</mi><mn>1</mn></msub><mo>+</mo><msub><mi>k</mi><mi>d</mi></msub></mrow><mo>)</mo></mrow></mrow><mo></mo><msub><mi>I</mi><msub><mi>SC</mi><mn>1</mn></msub></msub></mrow><mo>+</mo><mrow><mi>J</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mtd></mtr><mtr><mtd><mrow><msub><mover><mi>I</mi><mo>.</mo></mover><msub><mi>SC</mi><mn>2</mn></msub></msub><mo>=</mo><mrow><mrow><mrow><mo></mo><msub><mi>k</mi><mn>2</mn></msub></mrow><mo></mo><msub><mi>I</mi><msub><mi>SC</mi><mn>2</mn></msub></msub></mrow><mo>+</mo><mrow><msub><mi>k</mi><mn>1</mn></msub><mo></mo><msub><mi>I</mi><msub><mi>SC</mi><mn>1</mn></msub></msub></mrow></mrow></mrow></mtd></mtr></mtable><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mrow><msub><mi>I</mi><mi>P</mi></msub><mo></mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mrow><mrow><msub><mi>I</mi><mi>Pb</mi></msub><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mrow><msub><mi>I</mi><mi>L</mi></msub><mo></mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mrow><mrow><msub><mi>I</mi><mi>Lb</mi></msub><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mrow><mi>I</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mrow><mrow><mrow><mrow><msub><mi>I</mi><mi>P</mi></msub><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>/</mo><msub><mi>V</mi><mi>i</mi></msub></mrow><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mrow><msub><mi>I</mi><msub><mi>SC</mi><mn>1</mn></msub></msub><mo></mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mrow><mrow><mrow><msub><mi>J</mi><mi>b</mi></msub><mo>/</mo><msub><mi>k</mi><mn>1</mn></msub></mrow><mo>+</mo><mrow><msub><mi>k</mi><mi>d</mi></msub><mo></mo><mstyle><mtext></mtext></mstyle><mo></mo><mrow><msub><mi>I</mi><msub><mi>SC</mi><mn>2</mn></msub></msub><mo></mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow></mrow></mrow><mo>=</mo><mrow><msub><mi>k</mi><mn>1</mn></msub><mo></mo><mrow><mrow><msub><mi>I</mi><msub><mi>SC</mi><mn>1</mn></msub></msub><mo></mo><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow><mo>/</mo><msub><mi>k</mi><mn>2</mn></msub></mrow></mrow></mrow></mrow></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>2</mn></mrow></mtd></mtr></mtable></math></maths>
I<sub>p </sub>denotes the insulin mass in plasma, I<sub>L </sub>the insulin mass in the Liver, and I denote the concentration of plasma insulin, therefore Vi is the diffusion volume of the plasma compartment. Suffix b denotes basal state, J subcutaneous insulin injection (pmol/kg/min), m<sub>1</sub>, m<sub>2</sub>, m<sub>4 </sub>(min1) rate parameters. Degradation, D, occurs both in the liver and in the periphery. Peripheral degradation has been assumed linear (m<sub>4</sub>). It should be appreciated that alternative solutions of the aforementioned equation may be implemented to achieve the objective of the present invention.
Modification of Insulin Regimen Using the EMMGKAssuming that we have an optimal insulin injection schedule J(t), which can be a closed loop control, an open loop control, or any insulin management plan that includes a continuous injection component. Using the EMMGK we can derive an optimal adaptation to exercise of this injection schedule as follow:
Since<maths id="MATHUS00007" num="00007"><math overflow="scroll"><mrow><mover><mi>G</mi><mo>.</mo></mover><mo>=</mo><mrow><mrow><mo></mo><mrow><msub><mi>p</mi><mn>1</mn></msub><mo></mo><mrow><mo>(</mo><mrow><mi>G</mi><mo></mo><msub><mi>G</mi><mi>b</mi></msub></mrow><mo>)</mo></mrow></mrow></mrow><mo></mo><mrow><mrow><mo>(</mo><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Y</mi></mrow></mrow><mo>)</mo></mrow><mo></mo><mrow><mi>X</mi><mo>·</mo><mi>G</mi></mrow></mrow><mo>+</mo><mfrac><mi>D</mi><msub><mi>V</mi><mi>g</mi></msub></mfrac></mrow></mrow></math></maths>
and considering we can only act on insulin, id est the value of X. We can compute the value of X that would ensure no visible effect of exercise:
<maths id="MATHUS00008" num="00008"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>(</mo><mi>a</mi><mo>)</mo></mrow></mtd><mtd><mrow><mover><mi>X</mi><mo>~</mo></mover><mo>=</mo><mfrac><mi>X</mi><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Y</mi></mrow></mrow></mfrac></mrow></mtd></mtr></mtable></math></maths>
defining
<maths id="MATHUS00009" num="00009"><math overflow="scroll"><mrow><mrow><msub><mi>S</mi><mi>I</mi></msub><mo>=</mo><mfrac><msub><mi>p</mi><mn>2</mn></msub><msub><mi>p</mi><mn>3</mn></msub></mfrac></mrow><mo>,</mo></mrow></math></maths>
and CL to be the insulin clearance, we have
<maths id="MATHUS00010" num="00010"><math overflow="scroll"><mtable><mtr><mtd><mrow><mo>(</mo><mi>b</mi><mo>)</mo></mrow></mtd><mtd><mrow><msub><mi>X</mi><mi>∞</mi></msub><mo>=</mo><mrow><msub><mi>S</mi><mi>I</mi></msub><mo></mo><mfrac><mrow><msub><mi>J</mi><mi>∞</mi></msub><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow><mi>CL</mi></mfrac></mrow></mrow></mtd></mtr></mtable></math></maths>
where J<sub>b </sub>is the injection needed to obtain the plasma insulin concentration I<sub>b </sub>therefore, we obtain a new injection scheduled derive from equation (a) and (b)
<maths id="MATHUS00011" num="00011"><math overflow="scroll"><mtable><mtr><mtd><mrow><mrow><msub><mi>S</mi><mi>I</mi></msub><mo></mo><mfrac><mrow><mover><mi>J</mi><mo>~</mo></mover><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow><mi>CL</mi></mfrac></mrow><mo>=</mo><mrow><mrow><mrow><msub><mi>S</mi><mi>I</mi></msub><mo></mo><mfrac><mrow><mi>J</mi><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow><mrow><mi>CL</mi><mo></mo><mrow><mo>(</mo><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Z</mi></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mi>Y</mi></mrow></mrow><mo>)</mo></mrow></mrow></mfrac></mrow><mo></mo><mstyle><mtext></mtext></mstyle><mo>⇒</mo><mrow><mover><mi>J</mi><mo>~</mo></mover><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mo>=</mo><mrow><mfrac><mrow><mi>J</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo>+</mo><mrow><mfrac><mrow><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow></mrow></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>3.1</mn></mrow></mtd></mtr></mtable></math></maths>
For short term insulin dosing, the following equation represents the injection schedule:
<maths id="MATHUS00012" num="00012"><math overflow="scroll"><mtable><mtr><mtd><mrow><mrow><mover><mi>J</mi><mo>~</mo></mover><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><mfrac><mrow><mi>J</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo>+</mo><mrow><mfrac><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>β</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Y</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>3.2</mn></mrow></mtd></mtr></mtable></math></maths>
where {tilde over (J)}(t) is an optimal injection schedule adapted to physical activity at time t, J(t) is an optimal injection schedule at time t, Y(t) represents the transient variation in metabolic activity, J<sub>b </sub>is injection needed to obtain the plasma concentration I<sub>b</sub>, β represents the short term metabolic demand to heart rate ratio.For long term insulin dosing, the following equation represents the injection schedule:
<maths id="MATHUS00013" num="00013"><math overflow="scroll"><mtable><mtr><mtd><mrow><mrow><mover><mi>J</mi><mo>~</mo></mover><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><mfrac><mrow><mi>J</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo>+</mo><mrow><mfrac><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow><mrow><mn>1</mn><mo>+</mo><mrow><mi>α</mi><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><mi>Z</mi><mo></mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow></mrow></mrow></mfrac><mo></mo><msub><mi>J</mi><mi>b</mi></msub></mrow></mrow></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>3.3</mn></mrow></mtd></mtr></mtable></math></maths>
where {tilde over (J)}(t) is an optimal injection schedule adapted to physical activity at time t, J(t) is an optimal injection schedule at time t, Z(t) is the longterm change in insulin sensitivity due to physical activity at time t, J<sub>b </sub>is injection needed to obtain the plasma concentration I<sub>b</sub>, and α is the long term change in amplitude.
Using Spectral Analysis of the First Order Difference RWhile spectral analysis of the RRinterval is a commonly accepted tool to characterize changes in cardiac activity during exercise [46],[47], its use as a realtime detector of physical activity has not yet been presented as part of an insulin management system. This could be in part due to the difficulty of extracting meaningful spectral information from the heart rate signal, as well as to confounding effects such as autonomic neuropathy in diabetes. While an embodiment of the present invention uses the changes in heart rate spectral characteristics, the present invention provides a novel index to detect exercise, as part of an insulin management system.
The proposed index is as follow:
<maths id="MATHUS00014" num="00014"><math overflow="scroll"><mtable><mtr><mtd><mrow><msub><mi>I</mi><mi>EX</mi></msub><mo>=</mo><mfrac><mrow><munder><mo>∑</mo><mrow><mi>υ</mi><mo>></mo><mrow><mn>0.15</mn><mo></mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mi>Hz</mi></mrow></mrow></munder><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><msub><mi>P</mi><mi>t</mi></msub><mo></mo><mrow><mo>(</mo><mi>υ</mi><mo>)</mo></mrow></mrow></mrow><mrow><munder><mo>∑</mo><mrow><mi>υ</mi><mo>≤</mo><mrow><mn>0.15</mn><mo></mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mi>Hz</mi></mrow></mrow></munder><mo></mo><mstyle><mspace width="0.3em" height="0.3ex"/></mstyle><mo></mo><mrow><msub><mi>P</mi><mi>t</mi></msub><mo></mo><mrow><mo>(</mo><mi>υ</mi><mo>)</mo></mrow></mrow></mrow></mfrac></mrow></mtd><mtd><mrow><mi>Eq</mi><mo>.</mo><mstyle><mspace width="0.8em" height="0.8ex"/></mstyle><mo></mo><mn>4</mn></mrow></mtd></mtr></mtable></math></maths>
Where P<sub>t</sub>(Υ) is an estimate of the power spectrum of the first order difference of the heart rate signal at time t and frequency Υ. The signal is resampled at equal intervals (2 Hz) for proper use of Fourier techniques, and the estimate is obtained by computing the time frequency representation of the signal on the first order difference of the RR signal, using wavelet denoising of the TF representation, and moving average smoothing (both in time and frequency domain of width 5). It should be appreciated that alternative solutions of the aforementioned equations may be implemented to achieve the objective of the present invention.
Algorithmic Implementation of the EMMGKAn embodiment of the method may have three principal components. Here these components are presented sequentially, however, each of them can be used separately in an implementation independent from the others:
 Component 1: Exercise detector;
 Component 2: Estimator of increase in metabolic demand due to physical activity;
 Component 3: Recommendation of insulin dosing change to compensate for exercise.
The realtime detection of the changes in insulin sensitivity due to physical activity relies on the acquisition of a data stream that is available from continuous monitoring, HR monitoring, and reporting of insulin pump infusion rate. Thus:
Step 1 [components 1, 2, and 3] of the algorithm is to acquire realtime data from the following sources:
 1. CGM data, typically a time series of frequent BG determinations generated at a rate of one data point every 1 to 10 minutes;
 2. Insulin delivery data from insulin pump, including basal rate and boluses;
 3. Heart rate data from HR monitor acquired in short time intervals, e.g. 5 sec.These three data sources are synchronized to produce a timestamped threedimensional time series of vectors (BG(t), I(t), HR(t)), which is submitted to the model identification procedure.Step 2 [components 1, and 2] includes identifying of basal heart rate parameters for each individual during rest (e.g. overnight). This is the “training phase” of the method, which allows the EMMGK to be tailored to the specifics of the metabolic system of each person;
 1. HR<sub>b </sub>is defined as the overnight average heart rate.
 2. basal I<sub>EX </sub>(I<sub>EXb</sub>) is defined as the average I<sub>EX </sub>overnigtht.Step 3 [component 1] detection of exercise.
 1. resample last 10 minutes HR signal at 1 Hz using cubic spline
 2. compute Fast Fourier Transform (FFT) of resampled HR signal with bandwith smoothing ω=0.05 Hz
 3. compute I<sub>EX </sub>based on FFT results.
 4. If I<sub>EX</sub>>2*I<sub>EXb </sub>AND HR>1.3*HR<sub>b</sub>, exercise is detected.Step 4 [components 2, and 3] includes detection of deviations from basal state using HR and BG information. These deviations are quantified using the EMMGK as follows:
 1. the heart rate signal is smoothed using a Moving Average algorithm
 2. the resulting signal is used as an input in equation 3 and 4 of the EMMGK (Z and Y are initialized at 0 ). The differential equations are solved up to actual time.
 3. current values of Y and Z are reported.Step 5 [component 2] includes computation of the change in metabolic demand.
 1. get actual Y and Z values
 2. insulin dependent glucose utilization is increased by αZ+βY percentsStep 6 [component 3] includes recommendation of changes in insulin delivery to account for metabolic changes in step 5. These changes are quantified as follows:
 1. For openloop implementation:
 a. Get actual Z value
 b. Divide insulin regimen by (1+αZ)
 2. For closedloop implementation: Defining the actuation period (time between 2 consecutive update of the insulin injection) as τ,
 a. Get actual Y and Z values
 b. Adapt closed loop insulin prescription as per equation 1.4; if J<sub>b </sub>is not available, fix I<sub>b </sub>to 0, i.e. J<sub>b</sub>=0, and divide suggested injection by (1+αZ+βY)Step 7 [component 3] is the presentation of output from the procedure described in Steps 1to6. The format of the output depends on the mode of application of the method as follows:
 1 For openloop control applications, a reduction in the basal pump rate and/or reduction in the subsequent insulin bolus will be recommended to the patient in units of insulin upon detection of exercise;
 2. For automated closedloop control application, reduced pump rate and reduced bolus amounts will be directly transmitted to the insulin pump, using online HR monitoring.
This index was computed before, during, and after a low intensity ( 50% V<sub>O2max</sub>lactate threshold) exercise bout in 35 T1DM patients, during 2 inpatient days at the General Clinical Research Center at the University of Virginia (70 traces total). While only some patients presented the expected (from literature) drop in beat to beat interval variability, see FIG. 5 top panel, almost all (79%) presented a very clear peak in the I<sub>EX </sub>index during physical activity. A representative trace is presented in FIG. 5, lower panel.
Validation of the EMMGKWe have run two GCRC protocols pertaining to the effect of exercise in health and in T1DM:
Protocol #1 (GCRC code WLC015):
 Subjects: Thirtynine subjects with TIDM were recruited through regional advertisement. Exclusion criteria were age>65 years, mental retardation, psychological diagnoses or active substance abuse. The average age of the participants was 42.5 years±12, the average duration of T1DM was 21.6+9.4 years, the average HbAlc was 7.4+0.8%; there were 16 males.
 Procedure: Subjects were admitted to the University of Virginia GCRC in the evening prior to the study and their BG levels were controlled overnight within the target range of 100150 mg/dl, preventing hypoglycemia (BG<70mg/dl). Two hyperinsulinemic clamps were performed on two consecutive days: Each clamp used constant insulin infusion rate=1 mU/kg/min and variable glucose infusion rate to achieve and maintain BG levels at approximately 110 mg/dl. Subsequently, the glucose infusion rate was reduced to permit a controlled decline in BG of approximately 1 mg/dl/min until BG reached ˜50 mg/dl. Glucose infusion was then resumed to allow a recovery to normal glucose levels. The euglycemic portion of the clamp study varied in length from 70 to 210 minutes, and included 15 minutes of exercise at 50% V<sub>O2max</sub>lactate and a 20 minutes recovery period. The duration of the BG reduction procedure ranged from 30 to 60 minutes, the recovery ranged from 30 to 60 minutes. Because insulin was not measured during the protocol, the plasma concentration was estimated using population parameters for volume of insulin dispersion and half life of insulin in plasma. Therefore, insulin concentration is derived from injected insulin, I<sub>b </sub>“measured” as the steady state of the basal injection before the beginning of the clamp, a technique similar to the insulin kinetics model presented in the precious section.
 Results: As an example we present the curve of day 1 of subject 121 (FIG. 6). While the MMGK (which has fixed insulin sensitivity and glucose usage) failed to properly follow the measured glucose trace, small changes (FIG. 6, panel C) in glucose usage and insulin sensitivity during and after exercise were sufficient to explain the discrepancy (FIG. 6, panel A). We also observed that a change in glucose usage during exercise and recovery is not enough to explain the increase in dextrose infusion.Using minimal model analysis tools, we assessed:
 1. Metabolic demand computed from glucose infusion rate increased by 50% within few minutes of initiation of exercise, from 4.58 to 6.62 mg/kg/min.
 2. During exercise insulin action X increased, beginning approximately 5 minutes after initiation; p<sub>2 </sub>increased from preexercise value of 0.009 to 0.34 min<sup>−1</sup>. The increase in S<sub>I </sub>was not significant (8.69 vs 8.86 min<sup>−1 </sup>per μU/ml) but S<sub>I</sub><sup>D </sup>increased from 2.03 10<sup>−4 </sup>to 8.43 10<sup>−4 </sup>min<sup>−1 </sup>per μU/ml.
 3. After exercise insulin action decayed with a slower than onset rate constant p<sub>2 </sub>0.19 min<sup>−1</sup>. S<sub>I </sub>during recovery was 7.21 min<sup>−1 </sup>per μU/ml and S<sub>I</sub><sup>D </sup>6.59 10<sup>−4 </sup>min<sup>−1 </sup>per μU/ml.
The observed increase in insulin action is depicted in FIG. 7. The protocol did not include an observation period long enough to capture exactly the timing of recovery and the return of glucose usage to basal values. Values in the literature for such a return range between 20 and 24 hours.
The EMMGK was able to follow glucose dynamics during and after exercise and, most importantly, to follow the descent into hypoglycemia, while avoiding unrealistic parameter values. The weighted sum of squared errors (WSSE) was significantly lower for EMMGK than for the standard MMGK (7.77 vs 18.6 p<0.01). However, comparing error of fit and parameter values is not sufficient to judge the superiority of a model, because EMMGK demands the estimation of 2 additional parameters. Therefore to fully compare EMMGK and MMGK we computed a modified Akaike information criterion (AIC) for each model and each subject. This criterion accounts for the number of parameters. The EMMGK showed significantly lower AIC values than the MMGK: −0.85 vs −0.25, p<0.05; therefore showing a significant advantage in using the EMMGK over the classic MMGK during and after exercise, as shown in FIG. 8:
Protocol #2 (GCRC code MDB001):
 Subjects: The MDB001 protocol was conducted in NovemberDecember 2006 at the UVa GCRC and enrolled 10 healthy volunteers ages 18 to 35. The protocol was designed to investigate the glucose/insulin equilibrium and dynamics in health during highly unstable physiological states, namely: (i) physical activity—both low and high intensity; (ii) nutrient ingestion. Both situations are common in daily life and have been identified as major obstacles to closed loop glucose control. The research plan of MDB001 included a GCRCbased investigation of the glucose/insulin dynamics during ingested and injected glucose as well as during physical activity periods.
 Procedure: To this effect the protocol included an oral glucose tolerance test (OGTT), an intravenous glucose tolerance test (IVGTT, considered a gold standard for assessment of glucose kinetics) and a 45minute exercise period, divided into low and highintensity phases.
 Results: Glucose traces (FIG. 9) show a very sharp decrease in glucose concentration and insulin concentration at onset of moderate exercise (minute 220), followed by counterregulation (verified by epinephrine measurement) which brings glucose back up during the intense exercise period, and a small decrease in insulin concentration (minute 250). The results confirm the dynamics of shortterm glucose increase attributed to the onset of exercise. No longterm effect of exercise on insulin sensitivity could be directly observed due to the counterregulatory response effect on S<sub>I </sub>(transient increase).
In summary, increasing scientific and industrial effort is focused on the development of closedloop systems (artificial pancreas) to control glucose metabolism of people with diabetes, particularly T1DM. Experiments are being conducted with continuous glucose monitors (CGM) coupled with insulin pumps and a control algorithm. While such systems have proven feasible in steady metabolic states, they fail during changing metabolic demands, such as meals and physical activity. Because physical activity is a major trigger of acute hypoglycemia in diabetes, the timely detection of metabolic changes is critical for the success of closedloop control. However, increased metabolic demand due to physical activity cannot be reliably detected via glucose monitoring alone.
An aspect of various embodiments of the present invention comprises, but not limited thereto, a method, system, computer program product, device and apparatus using changes in heart rate (HR) as a correlate to increased metabolic demand. Specifically, the invention consists of three algorithms: (i) detecting physical activity, its duration and intensity through HR; (ii) quantifying shortterm and longterm changes in insulin sensitivity due to physical activity, and (iii) computing recommended changes in insulin dose to compensate for the effects of physical activity on insulin sensitivity.
An aspect of the present invention technology and related method provides the capability to overcome one of the major limitations of openloop and closedloop control of diabetes—the inability to account for metabolic changes due to physical activity—by providing an additional information source through heart rate monitoring.
Continuous monitoring devices are rapidly developing and it is expected that they will become soon essential part of the mainstream treatment of diabetes. Insulin infusion pumps are on the market, and the first systems providing openloop control have been approved by the FDA (The Paradigm system by Medtronic Minimed, Nortridge, Calif.). Because the metabolic changes due to physical activity are a major obstacle to optimal openloop or closedloop glucose control, this invention will provide numerous advantages. An aspect of various embodiments of the present invention may provide a number of advantages, such as but not limited thereto, the following: automated detection of the onset of physical activity using changes in heart rate; quantitative evaluation of shortterm changes in insulin sensitivity during and shortly after physical activity; quantitative evaluation of longterm changes in insulin sensitivity following exercise; recommendations for changes in insulin dose corresponding to the changes in insulin sensitivity in openloop control systems and patient advisory systems; and automated realtime suggestion of changes in insulin basal rate and boluses in closedloop control systems.
Standard clinical practice includes recommendation for lowering insulin dose in T1DM prior to or during exercise. However, none of these recommendations based on direct evaluation of changes in insulin sensitivity. There is no fieldbased assessment of these changes; and in general there are no treatment recommendations using heart rate monitoring for any aspect of the treatment of diabetes.
An aspect of various embodiments of the presentation invention may provide a number of advantages, such as but not limited thereto, the following: (i) tracking of changes in insulin sensitivity from easily obtainable hear rate data; (ii) individualized assessment of the effects of physical activity; (iii) individualized recommendations for changes in insulin dosing to compensate for the effects of physical activity.
Exemplary SystemsFIG. 10 shows a block diagrammatic representation of one of the embodiments of the invention. Referring to FIG. 10, there is shown a block diagrammatic representation of the system 1010 comprising a blood glucose sensor system 1030, heart rate monitor 1040, controller 1050, and insulin delivery system 1060. The glucose meter system 1030 is used for reading, inter alia, insulin dosage and blood glucose level 1031 in the body 1070. The glucose sensor system 1030 generates a sensor signal 1032 representative of the blood glucose levels in the body and provides the sensor signal 1032 to the controller 1050. The heart rate monitor system generates a sensor signal 1042 representative of the heart rate of the body 1070 and provides the sensor signal 1042 to the controller 1050. The controller receives the sensor signal 1032 from the glucose sensor system 1030 and sensor signal 1042 from the heart rate monitor system 1040 and generates control signals 1051 that are communicated to the insulin delivery system 1060. The insulin delivery system 1060 receives the control signals 1051 and infuses insulin 1061 into the body 1070 in response to the control signals 1060. The controls signal and/or sensor signals, or any desirable or required signals, may be communicated among or between any of the modules. It should be appreciated that the system 1010 (and the related method and computer product) as shown may include all of the modules as illustrated or any combination of a partial selection of the modules.
The glucose sensor system 1030 may include a glucose sensor, sensor electrical components to provide power to the sensor and generate sensor signal, and a sensor communication system to carry the signal to the controller 1050. The sensor system may be enclosed in a housing separate from the other modules of the system 1010 or may be enclosed in a single housing with the other modules of the system 1010.
The heart rate monitor system 1040 may include a heart rate monitor, monitor electrical components to provide power to the sensor and generate signal 1042, and a communication system to carry the signal 1042 to the controller 1050. The heart rate monitor system 1040 may be enclosed a housing separate from the other modules of the system 1010 or may be enclosed in a single housing with the other modules of the system 1010.
The controller 1050 includes controller electrical components and software to generate control signals for the insulin delivery system 1060. The signals may be sent via wireless or wire means or any combinations thereof. In a particular embodiment, the controller 1050, insulin delivery system 1060, glucose sensor system 1030, and heart rate monitor system 1040 may communicate between or among one another via wire. In further alternative embodiments, the controller 1050, insulin delivery system 1060, glucose sensor system 1030, and heart rate monitor system 1040 may communicate between or among one another via cable, wires, circuitry, electrical traces, blue tooth, fiber optic lines, RF, IR, or ultrasonic transmitters and receivers. The controller may be housed in the infusion device housing or may have its own housing or may be included in a supplemental device.
In an embodiment, the insulin delivery system 1060 includes the infusion device and an infusion tube to infuse insulin into the body 1070. In particular embodiments, the infusion device includes infusion electrical components to activate an infusion motor, an infusion communication system to receive control signals 1051, and an infusion device housing to hold the infusion device.
An example of a glucose sensor system, controller, and insulin pump system is the Paradigm system by Medtronic Minimed or the like. An example of a heart rate monitor include the various types of the Polar Heart Rate Monitors or the like.
The modules of the system 1010 may be separate and singular as shown or may be integral with one another in combination. There may be multiple systems with any combination of the modules shown. Any combination of the modules may exist together in a single housing or in separate housing. Further, any of the modules of the system 1010 and signal means may be duplicated or modified as desired or required for intended use, operation, application or environment.
The method of the invention may be implemented using hardware, software or a combination thereof and may be implemented in one or more computer systems or other processing systems, such as a personal digital assistance (PDAs), equipped with adequate memory and processing capabilities. In an example embodiment, the invention may be implemented in software running on a general purpose computer 1100 as illustrated in FIG. 11. Computer system 1100 may include one or more processors, such as processor 1104. Processor 1104 may be connected to a communications infrastructure 1106 (e.g. a communications bus, crossover bar, or network). Computer system 1100 may include a display interface 1102 that forwards graphics, text, or other data from the communications infrastructure 1106 (or from a frame buffer not shown) for display on the display unit 1130. Display unit 1130 may be digital and/or analog.
Computer system 1100 may also include a main memory 1108, preferably random access memory (RAM), and may also include a secondary memory 1110. The secondary memory 1110 may include, for example, a hard disk drive 1112 and/or a removable storage drive 1114, representing a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory, etc. The removable storage drive 1114 reads from and/or writes to a removable storage unit 1118 in a well known manner. Removable storage unit 1118, represents a floppy disk, magnetic tape, optical disc, etc. which is read by and written to by removable storage drive 1114. As will be appreciated, the removable storage unit 1118 may include a computer usable storage medium having stored therein computer software and/or data.
In alternative embodiments, secondary memory 1110 may include other means for allowing computer programs or other instructions to be loaded into computer system 1100. Such means may include, for example, a removable storage unit 1122 and an interface 1120. Examples of such removable storage units/interfaces include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as a ROM, PROM, EPROM or EEPROM) and associated socket, and other removable storage units 1122 and interfaces 1120 which allow software and data to be transferred from the removable storage unit 1122 to computer system 1100.
Computer system 1100 may also include a communications interface 1124. Communications interface 1124 allows software and data to be transferred between computer system 1100 and external devices. Examples of communications interface 1124 may include a modem, a network interface (such as an Ethernet card), a communications port (e.g., serial or parallel, etc.), a PCMCIA slot and card, etc. Software and data transferred via communications interface 1124 may be in the form of signals 1128 which may be electronic, electromagnetic, optical or other signals capable of being received by communications interface 1124. Signals 1128 may be provided to communications interface 1124 via a communications path (i.e., channel) 1126. Channel 1126 carries signals 1128 and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an RF link, an infrared link, and other communications channels.
In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as various software, firmware, disks, drives, removable storage drive 1114, a hard disk installed in hard disk drive 1112, and signals. These computer program products (“computer program medium” and “computer usable medium”) are means for providing software to computer systems 1100. The invention includes such computer program products.
Computer programs (also called computer control logic or computer program logic) may be stored in main memory 1108 and/or secondary memory 1110. Computer programs may also be received via communications interface 1124. Such computer programs, when executed, enable computer system 1100 to perform the features of the present invention as discussed herein. In particular, the computer programs, when executed, enable processor 1104 to perform the functions of the present invention. Accordingly, such computer programs represent controllers of computer system 1100. In an embodiment where the invention is implemented using software, the software may be stored in a computer program product and loaded into computer system 1100 using removable storage drive 1114, hard drive 1112 or communications interface 1124. The control logic (software) or computer program logic (software), when executed by the processor 1104, causes the processor 1104 to perform the function of the invention as described herein.
In another embodiment, the invention is implemented primarily in hardware using, for example, hardware components such as application specific integrated circuits (AS<sub>I </sub>Cs). Implementation of the hardware state machine to perform the functions described herein will be apparent to persons skilled in the relevant art(s).
In yet another embodiment, the invention is implemented using a combination of both hardware and software.
In an example software embodiment of the invention, the methods described above may be implemented in SPSS control language, but could be implemented in other programs, such as, but not limited to, C++ program language or other programs available to those skilled in the art.
FIG. 12 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for detecting physical activity, its duration and intensity through HR. Referring to FIG. 12, data is acquired 1271. The data include heart rate data, and may include other data such as glucose data and/or insulin delivery data. Heart rate data may be acquired with, but not limited to, sampling periods less than or equal to 1 minute, sampling periods less than or equal to about 10 minutes, frequently, sampling periods less than or equal to about 15 minutes. Glucose data may be acquired frequently, with a sampling period less than or equal to about 15 minutes, or with other sampling periods. A physical activity index is then calculated 1272 using the acquired heart rate data. Subsequently or concurrently, the index and heart rate data is used to detect physical activity 1273. Physical activity may be detected at, but are not limited to, the completion of acquiring data, near contemporaneously to the latest acquisition data, after the completion of acquiring data, and in real time. It should be appreciated that the aforementioned periods, duration, sequence, timing and/or frequency may be altered as desired or required.
FIG. 13 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for quantifying shortterm and/or longterm changes in insulin sensitivity due to physical activity. Referring to FIG. 13, following the detection of physical activity 1273, the physical activity on glucose demand is evaluated 1374. This may include: evaluating the short term changes in glucose demand 1375, evaluating short term changes in glucose demand and long term changes in insulin action 1376, and/or evaluating the long term changes in insulin action 1377. A short term period may correspond to, but are not limited to, during and within about 15 minutes after physical activity, during and within about 1 hour after physical activity, during and within about 2 hours after physical activity. When evaluating the short term changes in glucose demand, the short term changes in glucose demand is quantified 1378, for example according to Eq. 1.3. When evaluating the long term and short term changes in glucose demand, the long term and short term changes in glucose demand is quantified 1379, for example according to Eq. 1.2. When evaluating the long term changes in glucose demand, the long term changes in insulin action is quantified 1380, for example according to Eq. 1.4. Long term changes correspond to, but are not limited to, at least about 2 hours after physical activity, during and within about 6 hours after physical activity, during and within about 12 hours after physical activity, during and within about 24 hours after physical activity, and during and at least about 24 hours after physical activity. It should be appreciated that the aforementioned periods, duration, sequence, timing and/or frequency may be altered as desired or required. It should be appreciated that alternative solutions of the aforementioned equations may be implemented to achieve the objective of the present invention.
FIG. 14 provides a simplified flowchart of an aspect of an exemplary embodiment of the present invention method, system and computer program product for computing recommended changes in insulin dose to compensate for the effects of physical activity on insulin sensitivity. Referring to FIG. 14, following the detection of physical activity 1273, the physical activity on glucose demand and insulin action is evaluated 1481. This may include: evaluating the short term changes in glucose demand and insulin sensitivity 1482, evaluating short term changes in glucose demand and long term changes in insulin action 1483, and/or evaluating the long term changes in glucose demand and insulin action 1484. A short term period may correspond to, but are not limited to, during and within about 15 minutes after physical activity, during and within about 1 hour after physical activity, during and within about 2 hours after physical activity. When evaluating the short term changes in glucose demand and insulin sensitivity, the short term changes in glucose demand and insulin sensitivity is quantified 1485, for example according to equation Eq. 1.3. Subsequently, recommendations of insulin dosing 1488 are indicated. In both closed loop 1490 and open loop 1489 applications, basal pump rates and insulin bolus are reduced. In closed loop systems, the injection schedule for short term glucose changes is given by Eq. 3.2. When evaluating the long term and short term changes in glucose demand and insulin sensitivity, the short term changes in glucose demand and long term changes in insulin action is quantified 1486, for example according to Eq. 1.2. Subsequently, recommendations of insulin dosing 1491 are indicated. In both closed loop 1493 and open loop 1492 applications, basal pump rates and insulin bolus are reduced. In closed loop systems, the injection schedule for long term and short term glucose changes is given by Eq. 3. 1. When evaluating the long term changes in glucose demand and insulin sensitivity, the long term changes in glucose demand and insulin action is quantified 1487, for example according to Eq. 1.4. Long term changes correspond to, but are not limited to, at least about 2 hours after physical activity, during and within about 6 hours after physical activity, during and within about 12 hours after physical activity, during and within about 24 hours after physical activity, and during and at least about 24 hours after physical activity. Subsequently, recommendations of insulin dosing 1494 are indicated. In both closed loop 1496 and open loop 1495 applications, basal pump rates and insulin bolus are reduced. In closed loop systems, the injection schedule for long term glucose changes is given by Eq. 3.3. It should be appreciated that the aforementioned periods, duration, sequence, timing and/or frequency may be altered as desired or required. It should be appreciated that alternative solutions of the aforementioned equations may be implemented to achieve the objective of the present invention.
It should be appreciated that various aspects of embodiments of the present method, system and computer program product may be implemented with the following methods, systems and computer program products disclosed in the following U.S. Patent Applications, U.S. Patents, and PCT International Patent Applications that are hereby incorporated by reference herein:
1. U.S. Pat. No. 6,572,545 entitled “Method and apparatus for realtime control of physiological parameters;”
2. U.S. Pat. No. 6,399,341 entitled, “Artificial pancreas;”
3. U.S. Pat. No. 6,023,009 entitled, “Artificial pancreas;”
4. U.S. Pat. No. 5,262,055 entitled, “Implantable and refillable biohybrid artificial pancreas;”
5. U.S. Pat. No. 5,116,494 entitled, “Artificial pancreatic perfusion device with temperature sensitive matrix;”
6. U.S. Pat. No. 5,116,493 entitled, “Artificial pancreatic perfusion device with reseedable matrix;”
7. U.S. Pat. No. 5,109,866 entitled, “Artificial pancreas;”
8. U.S. Pat. No. 5,009,230 entitled, “Personal glucose monitor;”
9. U.S. Pat. No. 5,002,661 entitled, “Artificial pancreatic perfusion device;”
10. U.S. Pat. No. 4,936,317 entitled, “Cardiovascular prosthetic devices and implants with porous systems;”
11. U.S. Pat. No. 4,901,728 entitled, “Personal glucose monitor;”
12. U.S. Pat. No. 4,805,624 entitled, “Lowpotential electrochemical redox sensors;”
13. U.S. Pat. No. 4,636,144 entitled, “Microfeed pump for an artificial pancreas;”
14. U.S. Pat. No. 4,627,836 entitled, “Cardiovascular prosthetic devices and implants with porous systems;”
15. U.S. Pat. No. 4,515,584 entitled, “Artificial pancreas;”
16. U.S. Pat. No. 4,459,252 entitled, “Method of forming a small bore flexible vascular graft involving eluting solventelutable particles from a polymeric tubular article;”
17. U.S. Pat. No. 4,374,669 entitled, “Cardiovascular prosthetic devices and implants with porous systems;”
18. U.S. Pat. No. 4,355,426 entitled, “Porous flexible vascular graft;”
19. U.S. Pat. No. 4,281,669 entitled, “Pacemaker electrode with porous system;”
20. U.S. Pat. No. 4,242,460 entitled, “Cell culture device;”
21. U.S. Pat. No. 4,242,459 entitled, “Cell culture device;”
22. U.S. Pat. No. 4,053,952 entitled, “Magnetic fluid actuated control valve, relief valve and pump;”
It should be appreciated that various aspects of embodiments of the present method, system and computer program product may be implemented with the following methods, systems and computer program products disclosed in the following U.S. Patent Applications, U.S. Patents, and PCT International Patent Applications that are hereby incorporated by reference herein and coowned with the assignee:
PCT International Application Ser. No. PCT/US2005/013792, filed Apr. 21, 2005, entitled “Method, System, and Computer Program Product for Evaluation of the Accuracy of Blood Glucose Monitoring Sensors/Devices;”
U.S. patent application Ser. No. 11/578,831, filed Oct. 18, 2006 entitled “Method, System and Computer Program Product for Evaluating the Accuracy of Blood Glucose Monitoring Sensors/Devices;”
PCT International Application Ser. No. PCT/US01/09884, filed Mar. 29 2001, entitled “Method, System, and Computer Program Product for Evaluation of Glycemic Control in Diabetes SelfMonitoring Data;”
U.S. Pat. No. 7,025,425 B2 issued Apr. 11, 2006, entitled “Method, System, and Computer Program Product for the Evaluation of Glycemic Control in Diabetes from SelfMonitoring Data;”
U.S. patent application Ser. No. 11/305,946 filed Dec. 19, 2005 entitled “Method, System, and Computer Program Product for the Evaluation of Glycemic Control in Diabetes from SelfMonitoring Data;”
PCT International Application Ser. No. PCT/US2003/025053, filed Aug. 8, 2003, entitled “Method, System, and Computer Program Product for the Processing of SelfMonitoring Blood Glucose (SMBG) Data to Enhance Diabetic SelfManagement;”
U.S. patent application Ser. No. 10/524,094 filed Feb. 9, 2005 entitled “Managing and Processing SelfMonitoring Blood Glucose;”
PCT International Application Ser. No PCT/US2006/033724, filed Aug. 29, 2006, entitled “Method for Improvising Accuracy of Continuous Glucose Sensors and a Continuous Glucose Sensor Using the Same;”
PCT International Application No. PCT/US2007/000370, filed Jan. 5, 2007, entitled “Method, System and Computer Program Product for Evaluation of Blood Glucose Variability in Diabetes from SelfMonitoring Data;”
U.S. patent application Ser. No. 11/925,689, filed Oct. 26, 2007, entitled “For Method, System and Computer Program Product for RealTime Detection of Sensitivity Decline in Analyte Sensors;”
PCT International Application No. PCT/US00/22886, filed Aug. 21, 2000, entitled “Method and Apparatus for Predicting the Risk of Hypoglycemia;”
U.S. Pat. No. 6,923,763 B1, issued Aug. 2, 2005, entitled “Method and Apparatus for Predicting the Risk of Hypoglycemia;”
PCT International Patent Application No. PCT/US2007/082744, filed Oct. 26, 2007, entitled “For Method, System and Computer Program Product for RealTime Detection of Sensitivity Decline in Analyte Sensors;” and
U.S. patent application Ser. No. 11/943,226, filed Nov. 20, 2007, entitled “Systems, Methods, and Computer Program Codes for Recognition of Patterns of Hyperglycemia and Hypoglycemia, Increase Glucose Variability, and Ineffective Selfmonitoring in Diabetes.”
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In summary, while the present invention has been described with respect to specific embodiments, many modifications, variations, alterations, substitutions, and equivalents will be apparent to those skilled in the art. The present invention is not to be limited in scope by the specific embodiment described herein. Indeed, various modifications of the present invention, in addition to those described herein, will be apparent to those of skill in the art from the foregoing description and accompanying drawings. Accordingly, the invention is to be considered as limited only by the spirit and scope of the following claims, including all modifications and equivalents.
Still other embodiments will become readily apparent to those skilled in this art from reading the aboverecited detailed description and drawings of certain exemplary embodiments. It should be understood that numerous variations, modifications, and additional embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of this application. For example, regardless of the content of any portion (e.g., title, field, background, summary, abstract, drawing figure, etc.) of this application, unless clearly specified to the contrary, there is no requirement for the inclusion in any claim herein or of any application claiming priority hereto of any particular described or illustrated activity or element, any particular sequence of such activities, or any particular interrelationship of such elements. Moreover, any activity can be repeated, any activity can be performed by multiple entities, and/or any element can be duplicated. Further, any activity or element can be excluded, the sequence of activities can vary, and/or the interrelationship of elements can vary. Unless clearly specified to the contrary, there is no requirement for any particular described or illustrated activity or element, any particular sequence or such activities, any particular size, speed, material, dimension or frequency, or any particularly interrelationship of such elements. Accordingly, the descriptions and drawings are to be regarded as illustrative in nature, and not as restrictive. Moreover, when any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. When any range is described herein, unless clearly stated otherwise, that range includes all values therein and all sub ranges therein. Any information in any material (e.g., a United States/foreign patent, United States/foreign patent application, book, article, etc.) that has been incorporated by reference herein, is only incorporated by reference to the extent that no conflict exists between such information and the other statements and drawings set forth herein. In the event of such conflict, including a conflict that would render invalid any claim herein or seeking priority hereto, then any such conflicting information in such incorporated by reference material is specifically not incorporated by reference herein.