Calibration of glucose monitoring sensor and/or insulin delivery system

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 variable includes a current signal corresponding to said sensor measurements.

21. 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 linear Kalman filter technique in which a parameter vector includes a calfactor variable and an offset variable.

22. The apparatus of claim 12 , further comprising:

the one or more subcutaneous current sensors adapted to be coupled to the patient to obtain the blood-glucose sensor measurements and adapted to provide said one or more signals based on said blood-glucose sensor measurements; and

wherein the at least one insulin delivery system is adapted to infuse insulin into the patient based on said function for estimating a blood-glucose concentration in the patient.

23. An article comprising:

at least one storage medium having stored thereon instructions executable by one or more processors to:

receive sensor measurements from a patient 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;

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

control therapy delivery based on the determined function for estimating the blood-glucose concentration.