Method, system, and computer program product for improving the accuracy of glucose sensors using insulin delivery observation in diabetes

Patent metadata

Field	Value
Publication number	US-9398869-B2
Application number	US-201113637359-A
Country	US
Kind code	B2
Filing date	Mar 24, 2011
Priority date	Mar 26, 2010
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

Method and System for providing a signal from an insulin pump, artificial pancreas, or another insulin delivery device as a source of information for improving the accuracy of a continuous glucose sensor (CGS). The effect of using insulin information to enhance sensor accuracy is most prominent at low blood glucose levels, i.e. in the hypoglycemic range, which is critical for any treatment. A system for providing a filtering/state estimation methodology that may be used to determine a glucose state estimate at time t-τ. The estimation may be extrapolated to some future time t and then the extrapolated value is used to extract the blood glucose component. The blood glucose component of the extrapolation and the output of the CGS are weighted and used to estimate the blood glucose level of a subject.

First claim

We claim:

1. A processor implemented method for improving the accuracy of a glucose measurement device, said method comprising:
obtaining a glucose level readout of a subject, from said glucose measurement device;
obtaining insulin delivery information from an insulin delivery device;
performing a first intermediary computation using said glucose level readout from said glucose measurement device and said insulin delivery information, to obtain an output of said first intermediary computation;
performing a second intermediary computation using said output of said first intermediary computation to obtain an output of said second intermediary computation;
performing a third computation to reach an estimate of the blood glucose of the subject by applying a weighting scheme to said readout from the glucose measurement device and said output of said second intermediary computation; and
determining, based at least in part on said estimate of the blood glucose of the subject, an amount of insulin to be delivered to the subject by the insulin delivery device;
wherein the insulin delivery device is configured to deliver the determined amount of insulin to the subject.

2. The method of claim 1 , wherein said glucose measurement device is a continuous glucose device.

3. The method of claim 1 , wherein said first intermediary computation further comprises a Kalman Filter methodology.

4. The method of claim 1 , wherein said first intermediary computation further comprises a method for filtering/state estimation using one of: an H-infinity filtering method, a Bayesian filtering method, a Monte Carlo method, and a least squares method.

5. The method of claim 1 , wherein said readout from said glucose measurement device provides a periodic glucose readout.

6. The method of claim 5 , wherein the frequency of said readout from said glucose measurement device is at least approximately every 60 minutes.

7. The method of claim 5 , wherein the frequency of said readout from said glucose measurement device is at least approximately every 30 minutes.

8. The method of claim 5 , wherein the frequency of said readout from said glucose measurement device is at least approximately every 15 minutes.

9. The method of claim 1 , wherein said insulin delivery information is provided by an insulin pump, artificial pancreas, or another insulin delivery device.

10. The method of claim 1 , wherein said insulin delivery information is provided by a measuring device.

11. The method of claim 1 , wherein said second intermediary computation further comprises:
inferring said output of said second intermediary computation from said output of said first intermediary computation.

12. The method of claim 11 , wherein inferring said second intermediary computation further comprises:
extrapolating said output of said first intermediary computation to some future time to determine an extrapolated state vector output.

13. The method of claim 12 , wherein determining said extrapolated output is provided by {circumflex over (x)}(t|t−τ)=A τ {circumflex over (x)}(t−τ)+A(τ)Bu(t−τ)+A(τ)Gω(t−τ), wherein {circumflex over (x)}(t|t−τ) refers to the extrapolated state vector output;
A is a state space matrix;
B is a state space matrix;
G is a state space matrix;
A τ =A●A●●●A, i.e. the τ-fold composition of said state space matrix A;
A(T)=Σ s=0 τ−1 A s , with A (0)=0 8×8 .

14. The method of claim 13 , wherein said state space matrix A is:

A
=

⌊

.9913

-
102.7

-
1.50

×

10

-
8

-
2.89

×

10

-
6

-
4.1

×

10

-
4

0

2.01
×

10

-
6

4.30
×

10

-
5

0

.839

5.23
×

10

-
10

7.44
×

10

-
8

6.84
×

10

-
6

0

0

0

Assignees

• Kovatchev Boris P
• Breton Marc D
• Patek Stephen D
• Karvetski Colleen Hughes
• Univ Virginia Patent Foundation

Inventors

• Kovatchev Boris P
• Breton Marc D
• Patek Stephen D
• Karvetski Colleen Hughes

Classifications

• A61M5/142

  Pressure infusion, e.g. using pumps · CPC title

• A61B5/7225

  Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316) · CPC title

• A61B5/1495

  Calibrating or testing of in-vivo probes · CPC title

• A61B5/725

  using specific filters therefor, e.g. Kalman or adaptive filters (specific diagnostics methods using using bioelectric or biomagnetic signals A61B5/316) · CPC title

• A61B5/14532 Primary

  for measuring glucose, e.g. by tissue impedance measurement · CPC title