Calibration of glucose monitoring sensor and/or insulin delivery system

Patent metadata

Field	Value
Publication number	US-11266334-B2
Application number	US-201815907670-A
Country	US
Kind code	B2
Filing date	Feb 28, 2018
Priority date	Mar 26, 2010
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

Disclosed are methods, apparatuses, etc. for calibrating glucose monitoring sensors and/or insulin delivery systems. In certain example embodiments, blood glucose reference samples may be correlated with sensor measurements with regard to a delay associated with the sensor measurements. In certain other example embodiments, a blood-glucose concentration in a patient may be determined based, at least in part, on one or more probability models, one or more functions for estimating blood-glucose concentrations, and/or blood glucose reference sample-sensor measurement pairs.

First claim

What is claimed is:

1. A method comprising:
receiving sensor measurements from a patient, wherein said sensor measurements are taken using one or more subcutaneous current sensors;
correlating blood-glucose reference samples with said sensor measurements to provide at least one output signal associated with said sensor measurements,
wherein the correlating further comprises:
time shifting said sensor measurements by different numbers of samples defined by a plurality of time shift delays to generate a plurality of time-shifted sensor measurements; and
applying said blood-glucose reference samples and said plurality of time-shifted sensor measurements to a matched filter to ascertain a delay, said delay representing, at least partially, an approximated delay associated with glucose diffusion between blood plasma and interstitial fluid of the patient;

determining a function, that accounts for said delay, for estimating a blood-glucose concentration in the patient based, at least in part, on said at least one output signal; and
controlling therapy delivery based on the determined function for estimating the blood-glucose concentration.

2. The method of claim 1 , wherein said correlating comprises:
associating each blood-glucose reference sample of the blood-glucose reference samples with a respective sensor measurement of the sensor measurements to generate a plurality of blood-glucose reference sample-sensor measurement pairs; and
for each of the blood-glucose reference sample-sensor measurement pairs, cross-correlating the blood-glucose reference sample-sensor measurement pairs to measure a correlation for each time shift delay.

3. The method of claim 1 , wherein said correlating comprises:
for each time shift delay:
time-shifting said sensor measurements by a respective number of samples; and
correlating said time-shifted sensor measurements corresponding to that time shift delay with said blood-glucose reference samples.

4. The method of claim 1 , wherein said determining comprises:
applying said blood-glucose reference samples and said sensor measurements to a Wiener filter to determine multiple filter coefficients.

5. The method of claim 1 , wherein said determining further comprises:
determining the function for estimating the blood-glucose concentration in the patient from the sensor measurements based, at least in part, on a noise signal that is associated with said sensor measurements and said at least one output signal.

6. The method of claim 1 , wherein said sensor measurements comprise current sensor measurements taken from interstitial fluid of the patient.

7. The method of claim 1 , wherein said function accounts for said delay and a chemical reaction delay.

8. The method of claim 1 , wherein said determining further comprises:
determining a slope and an offset for said function for estimating the blood glucose concentration in the patient.

9. The method of claim 8 , wherein said determining further comprises:
determining said slope and said offset for said function using a Bayesian technique in which a parameter vector includes a calfactor variable and an offset variable and in which an independent variable includes a current signal corresponding to said sensor measurements.

10. The method of claim 8 , wherein said determining further comprises:
determining said slope and said offset for said function using a linear Kalman filter technique in which a parameter vector includes a calfactor variable and an offset variable.

11. The method of claim 1 , wherein said controlling therapy delivery includes:
infusing insulin into the patient based on said function for estimating a blood-glucose concentration in the patient.

12. An apparatus comprising:
a filter unit to receive one or more signals based on blood-glucose sensor measurements, said filter unit comprising one or more processors to:
receive the sensor measurements from a patient, wherein said sensor measurements are taken using one or more subcutaneous current sensors;
time shift said sensor measurements by different numbers of samples defined by a plurality of time shift delays to generate a plurality of time-shifted sensor measurements;
correlate blood-glucose reference samples with said plurality of time-shifted sensor measurements to provide at least one output signal by applying said blood-glucose reference samples and said plurality of time-shifted sensor measurements to a matched filter to ascertain a delay, said delay representing, at least partially, an approximated delay associated with glucose diffusion between blood plasma and interstitial fluid of the patient; and
determine a function, that accounts for said delay, for estimating a blood-glucose concentration in the patient based, at least in part, on said at least one output signal; and

at least one insulin delivery system configured to control therapy delivery based on the determined function for estimating the blood-glucose concentration.

13. The apparatus of claim 12 , wherein said filter unit is capable of correlating said blood-glucose reference samples with said plurality of time-shifted sensor measurements by:
associating each blood-glucose reference sample of the blood-glucose reference samples with a respective sensor measurement of the sensor measurements to generate a plurality of blood-glucose reference sample-sensor measurement pairs; and
for each group of blood-glucose reference sample-sensor measurement pairs, cross-correlating the blood-glucose reference sample-sensor measurement pairs to measure a correlation for each time shift delay.

14. The apparatus of claim 12 , wherein said filter unit is capable of correlating said blood-glucose reference samples with said plurality of time-shifted sensor measurements by:
for each time shift delay:
time-shifting said sensor measurements by a respective number of samples; and
correlating said time-shifted sensor measurements corresponding to that time shift delay with said blood-glucose reference samples.

15. The apparatus of claim 12 , wherein said filter unit is capable of determining said function for estimating said blood-glucose concentration in the patient by:
applying said blood-glucose reference samples and said sensor measurements to a Wiener filter to determine multiple filter coefficients.

16. The apparatus of claim 12 , wherein said filter unit is capable of determining said function for estimating said blood-glucose concentration in the patient from the sensor measurements based, at least in part, on a noise signal that is associated with said sensor measurements.

17. The apparatus of claim 12 , wherein said sensor measurements comprise current sensor measurements taken from interstitial fluid of the patient.

18. The apparatus of claim 12 , wherein said at least one insulin delivery system is further configured to:
determine an estimate for the blood glucose concentration based on the determined function.

19. The apparatus of claim 12 , wherein said filter unit is capable of determining said function for estimating said blood-glucose concentration in the patient by: determining a slope and an offset for said function.

20. The apparatus of claim 19 , wherein said filter unit is capable of determining said function for estimating said blood-glucose concentration in the patient by:
determining said slope and said offset for said function using a Bayesian technique in which a parameter vector includes a calfactor variable and an offset variable and in which an independent

Assignees

• Medtronic Minimed Inc

Inventors

• Roy Anirban
• Keenan Barry
• Kremliovsky Michael

Classifications

• A61B5/14532 Primary

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

• A61B5/1451

  for interstitial fluid · CPC title

• A61B5/7203

  for noise prevention, reduction or removal · CPC title

• A61B5/14865

  invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors · CPC title

• A61B5/4839

  combined with drug delivery · CPC title