ACCURACY OF CONTINUOUS GLUCOSE SENSORS

• US 20160007890A1
• Filed: 07/14/2015
• Published: 01/14/2016
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories), University of Virginia Patent Foundation (University of Virginia)
• Inventors: Kovatchev, Boris P., King, Christopher R.
• Granted Patent: US 10,194,850 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

A method, apparatus, and a kit are capable of improving accuracy of CGS devices using dynamic outputs of continuous glucose sensors.

Claims

1. A method for improving accuracy of a continuous glucose sensor (CGS), comprising:

calibrating the CGS at a first time; and

calibrating the COS at a second time that is determined based upon at least one of a dynamically monitored COS value and a rate of COS change.

2. The method of claim 1, wherein the dynamically monitored COS value differs by at least 15 mg/dl before the second calibration takes place.

3. The method of claim 1, wherein the dynamically monitored CGS value differs by at least 20 mg/dl before the second calibration takes place.

4. The method of claim 1, wherein the dynamically monitored CGS value differs by at least 30 mg/dl before the second calibration takes place.

5. The method of claim 1, further comprising:

dynamically monitoring the CGS value and the rate of COS change over time.

6. The method of claim 5, further comprising:

calculating the first order time derivative of the monitored CGS value;

determining whether the absolute value of the first time derivative of the COS value is substantially less than 1; and

maintaining the calibration of the COS at the first time when the absolute value of the first time derivative of the CGS value is substantially less than 1.

7. The method of claim 6, further comprising:

determining the absolute change between the COS at the second time and the COS at the first time calibration is greater than a pre-determined value when the absolute value of the first time derivative of the COS value is substantially less than 1; and

maintaining the calibration of the CGS at the first time when the absolute change between the CGS at the second time and the CGS at the first time calibration is greater than a predetermined value.

8. The method of claim 7, wherein the predetermined value is 30 mg/dl.

9. The method of claim 7, wherein the predetermined value is 40 mg/dl.

10. The method of claim 7, further comprising:

recalibrating the CGS when it is determined that the absolute change between the CGS at the second time and the CGS at the first time calibration is greater than a pre-determined value.

11. The method of claim 1, further comprising:

improving the accuracy of the CGS output by remedying a physiology time lag between the blood glucose level and a glucose level in an interstitial fluid that interacts with the blood glucose.

12. The method of claim 11, wherein the step of improving the accuracy further comprises:

deriving a mathematical equation describing a time dependence of CGS output on the blood glucose level;

deriving the time dependence blood glucose level as a function of the CGS output; and

applying the derived time dependence blood glucose level function to a set of CGS raw outputs so as to predict the blood glucose level at a later time or correcting the CGS output.

13. The method of claim 12, wherein the mathematical equation is derived based on a model that includes a description of a diffusion interaction between the blood glucose and glucose in the interstitial fluid.

14. The method of claim 12, wherein the mathematical equation is derived based on a model that includes a description of an assumption of the glucose in the interstitial fluid.

15. The method of claim 1, wherein the second time that is determined based upon both of the dynamically monitored CGS value and the rate of CGS change.

16. A method for improving the accuracy of a continuous glucose sensor, comprising:

calibrating the continuous glucose sensor using first blood glucose value and second blood glucose value;

measuring the first blood glucose value when the continuous glucose sensor measures a corresponding first interstitial glucose value; and

measuring the second blood glucose value when the continuous glucose sensor measures a corresponding second interstitial glucose value that is different from the first interstitial glucose value by a predetermined amount.

17-30. -30. (canceled)

31. A system for improving an accuracy of a continuous glucose sensor, comprising:

an accuracy improving module accessible to an output of the continuous glucose sensor, further comprising;

a decision making mechanism capable of determining a calibration at a time based upon at least one of a dynamically monitored output of the continuous glucose sensor.

32. The system of claim 31, wherein the decision making mechanism is capable of determining the calibration at the time that is based upon the output of the continuous glucose sensor and a rate of change of the output of the continuous glucose sensor.

33. The system of claim 31, wherein the accuracy improving module further comprises:

an initial request module capable of initiating a calibration at a predetermined time sequence.

34. The system of claim 33, wherein the decision making mechanism further comprises:

a monitoring module capable of dynamically monitoring the output from the continuous glucose sensor.

35-53. -53. (canceled)