Method of determining concentration of glucose in blood

• US 20020155615A1
• Filed: 02/05/2002
• Published: 10/24/2002
• Est. Priority Date: 02/05/2001
• Status: Active Grant

• Current Assignee: Glucosens Incorporated
• Original Assignee: Glucosens Incorporated
• Inventors: Novikov, Igor A., Kislov, Alexander V.
• Granted Patent: US 6,841,389 B2
• Time in Patent Office: Days
• US Class Current: 436/149
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: Y10T 436/104998 Glucose, ketone, nitrate standard or control
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A method of non-invasive determination of a glucose concentration in blood based on the measurements of the total impedance of the skin of a patient is disclosed. The method is based on a linear model of a first order correlation between the glucose concentration and the total impedance, the model taking into account the rate of change of the glucose concentration. The coefficients used in an approximating function are determined at the preliminary stage measurements by an invasive method.

Claims

1. A method of determining glucose concentration G(t) in blood of comprising:

measuring a total impedance of a skin and calculating G(t) according to an expression

$G<br><br>\left(t\right)=G_1<br><br>e^{-a_0<br><br>t}+q+a_1<br><br>e^{-a_0<br><br>t}<br><br>{\int <br><br>}_0^t<br><br>N<br><br>\left(x\right)<br><br>e^{a_0<br><br>x}<br><br><br><br>x;<br><br>$

 

performing preliminary stage measurements during a time interval T comprising measuring a total impedance of a skin and a glucose concentration G_inv(t) using an invasive method; and

using the determined total impedance and the glucose concentration G_inv(t) to determine parameters a₀, q and a₁ by approximating G_inv(t) to G(t) measured during the time interval T of the preliminary stage measurements.

2. The method of claim 1, wherein the time interval T is sufficient to observe the changes of glucose concentration related to the natural daily variations of the glucose concentration and the changes related to a diet, exercise, glucose or insulin injections.

3. The method of claim 1, further comprising performing preliminary stage measurements during an increase of the glucose concentration.

4. The method of claim 1, further comprising performing preliminary stage measurements during a decrease of the glucose concentration.

5. The method of claim 1, further comprising determining the parameters a₀, q and a₁, for the glucose concentrations below, above and approximately at a renal threshold of a patient.

6. The method of claim 1, further comprising correcting the glucose concentration G(t) at the renal threshold by making the G(t) equal to a value of the glucose concentration at the renal threshold obtained by the invasive method at the preliminary stage.

7. The method of claim 1, wherein measuring the total impedance comprises measuring a reactive component of the total impedance, an active component of the impedance, or a phase angle between the reactive and the active components.

8. The method of claim 1, wherein q=0 for an insulin-dependent patient.

9. The method of claim 1, wherein the time interval T is between about 4 hours and about 12 hours.

10. A method of determining glucose concentration G(t_m) in blood of comprising:

performing discreet measurements of a total impedance of a skin and calculating G(t_m) according to an expression

$G<br><br>\left(t_m\right)=G_1<br><br>e^{-a_0<br><br>t_m}+q+a_1<br><br>e^{-a_0<br><br>t_m}<br><br>\underset{k=1}{\overset{m}{\sum <br><br>}}<br><br>\left[N<br><br>\left(t_k\right)<br><br>e^{a_0<br><br>t_k}+N<br><br>\left(t_{k-1}\right)<br><br>e^{a_0<br><br>t_{k-1}}\right]<br><br>\frac{\left(t_k-t_{k-1}\right)}{2};<br><br>$

 

performing preliminary stage measurements during a time interval T comprising measuring a total impedance of a skin and a glucose concentration G_inv(t) using an invasive method; and

using the determined total impedance and the glucose concentration G_inv(t) to determine parameters a₀, q and a₁ by approximating G_inv(t) to G(t_m) measured during the time interval T of the preliminary stage measurements.

11. The method of claim 10, wherein the time interval T is sufficient to observe the changes of glucose concentration related to the natural daily variations of the glucose concentration and the changes related to a diet, exercise, glucose or insulin injections.

12. The method of claim 10, further comprising performing preliminary stage measurements during an increase of the glucose concentration.

13. The method of claim 10, further comprising performing preliminary stage measurements during a decrease of the glucose concentration.

14. The method of claim 10, further comprising determining the parameters a₀, q and a₁ for the glucose concentrations below, above and approximately at a renal threshold of a patient.

15. The method of claim 10, further comprising correcting the glucose concentration G(t_m) at the renal threshold by making the G(t_m) equal to a value of the glucose concentration at the renal threshold obtained by the invasive method at the preliminary stage.

16. The method of claim 10, wherein measuring the total impedance comprises measuring a reactive component of the total impedance, an active component of the impedance, or a phase angle between the reactive and the active components.

17. The method of claim 10, wherein q=0 for an insulin-dependent patient.

18. The method of claim 10, wherein the time interval T is between about 4 hours and about 12 hours.