Methods of Lag-Compensation for Analyte Measurements, and Devices Related Thereto

• US 20130304389A1
• Filed: 04/24/2013
• Published: 11/14/2013
• Est. Priority Date: 04/24/2012
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Budiman, Erwin S., Li, David L.
• Granted Patent: US 9,462,970 B2
• Time in Patent Office: Days
• US Class Current: 702/19
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

In some aspects, methods of lag compensation of analyte measurements are provided. Methods of lag-compensation are provided for analyte point measurements and/or for analyte rate-of-change measurements. The methods include receiving a series of uncompensated analyte measurements and determining parameter values for analyte point and/or rate-of-change estimates based on reference analyte measurements. The analyte rate-of-change estimate is based on a sum of a plurality of scaled rates-of-changes. The analyte point estimate is based on a sum of an analyte point and a sum of a plurality of scaled rates-of-changes. Devices related to the methods are also provided.

Claims

1. A method of lag compensation of glucose level measurements, comprising:

receiving one or more uncompensated glucose measurements prior to lag compensation;

determining a first set of weighting coefficients from a glucose level corresponding to measurements at an initial reference time and at least two scaled rates-of-changes from the initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time; and

calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the first parameter values.

2. The method of claim 1, wherein the determining of the first set of weighting coefficients comprises determining a first set of parameter values for a glucose level estimate based on one or more glucose measurements, wherein the glucose level estimate is based on a sum of:

a glucose level corresponding to measurements at an initial reference time; and

a sum of at least two scaled rates-of-changes, wherein the rates-of-changes comprise a first rate-of-change from the initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time.

3. The method of claim 2, wherein the first set of parameter values comprises:

a first scalar of the first rate-of-change;

the first prior reference time;

a second scalar of the second rate-of-change; and

the second prior reference time.

4. The method of claim 2, comprising:

determining a second set of parameter values for the glucose level estimate based on the reference glucose measurements;

wherein the first set and the second set of parameter values point to different sets of prior reference times.

5. The method of claim 4, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values; and

calculating lag-compensated glucose level measurements by averaging a first output and a second output;

wherein the first output is generated by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the first set of parameter values;

wherein the second output is generated by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the second set of parameter values.

6. The method of claim 4, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values; and

deriving a second set of weighting coefficients from the second set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time for the first set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values; and

when valid data is present at the first prior reference time and the second prior reference time for the second set of parameter values and not the first set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the second set of parameter values.

7. The method of claim 4, comprising:

determining a third set of parameter values for the glucose level estimate based on the reference glucose measurements;

wherein the first, second, and third sets of parameter values point to different sets of prior reference times.

8. The method of claim 7, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values;

deriving a third set of weighting coefficients from the third set of parameter values; and

calculating lag-compensated glucose level measurements by averaging available outputs, wherein the available outputs are generated by applying the first, second, and/or third sets of weighting coefficients to uncompensated glucose measurements received at the initial reference time and prior reference times of respective first, second, and/or third sets of parameter values which have valid data present.

9. The method of claim 8, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values;

deriving a third set of weighting coefficients from the third set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time for the first set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time for the first set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the second set of parameter values; and

when valid data is present at the first prior reference time and the second prior reference time of the third set of parameter values and not the first set or the second set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the third set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the third set of parameter values.

10. The method of claim 2, comprising:

determining three or more additional sets of parameter values for the glucose level estimate based on the reference glucose measurements;

wherein the three or more additional sets of parameter values point to different sets of prior reference times.

11. The method of claim 2, comprising:

determining a fourth set of parameter values for a second glucose level estimate;

wherein the second glucose level estimate is based on a sum of a glucose level and a sum of a plurality of scaled rates-of-changes;

wherein the glucose level corresponds to measurements at an alternate initial reference time, wherein the alternate initial reference time is prior to the initial reference time by a time delay;

wherein the rates-of-changes comprise;

a third rate-of-change from the alternate initial reference time to a fourth prior reference time with respect to the alternate initial reference time; and

a fourth rate-of-change from the alternate initial reference time to a fifth prior reference time with respect to the alternate initial reference time.

12. The method of claim 1, wherein the rates-of-changes comprise:

one or more additional rates-of-changes from the initial reference time to additional prior reference times.

13. The method of claim 12, wherein the first set of parameter values comprises:

the first scalar of the first rate-of-change;

the first prior reference time;

the second scalar of the second rate-of-change;

the second prior reference time;

additional scalars for the additional rates-of-changes; and

each of the additional prior reference times.

14. The method of claim 12, comprising:

receiving a series of uncompensated glucose measurements;

deriving weighting coefficients from the first set of parameter values; and

calculating lag-compensated glucose level measurements from the uncompensated glucose measurements;

wherein the lag-compensated glucose level measurements are calculated by applying the weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, at the second prior reference time, and each of the additional prior reference times.

15. A method of lag-compensation of glucose rate-of-change measurements, comprising:

receiving a series of uncompensated glucose measurements prior to lag compensation;

determining a first set of weighting coefficients from a plurality of scaled rates-of-changes comprising a first rate-of-change from an initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time; and

calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the first set of parameter values.

16. The method of claim 15, wherein the determining of the first set of weighting coefficients comprises determining a first set of parameter values for a glucose rate-of-change estimate based on reference glucose measurements, wherein the glucose rate-of-change estimate is based on a sum of a plurality of scaled rates-of-changes.

17. The method of claim 16, wherein the parameter values comprise:

a first scalar of the first rate-of-change;

the first prior reference time;

a second scalar of the second rate-of-change; and

the second prior reference time.

18. The method of claim 17, comprising:

determining a second set of parameter values for the glucose rate-of-change estimate based on the reference glucose measurements;

wherein the first set and the second set of parameter values point to different sets of prior reference times.

19. The method of claim 18, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values; and

calculating lag-compensated rate-of-change measurements by averaging a first output and a second output;

wherein the first output is generated by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values;

wherein the second output is generated by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values.

20. The method of claim 18, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time of the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values; and

when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values.

21. The method of claim 18, comprising:

determining a third set of parameter values for the glucose rate-of-change estimate based on the reference glucose measurements;

wherein the first set, second set, and third set of parameter values point to different sets of reference times.

22. The method claim 21, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values;

deriving a third set of weighting coefficients from the third set of parameter values; and

calculating lag-compensated rate-of-change measurements by averaging available outputs, wherein the available outputs are generated by applying the first, second, and/or third sets of weighting coefficients to uncompensated glucose measurements received at the initial reference time and prior reference times of respective first, second, and/or third sets of parameter values which have valid data present.

23. The method of claim 21, comprising:

receiving a series of uncompensated glucose measurements;

deriving a first set of weighting coefficients from the first set of parameter values;

deriving a second set of weighting coefficients from the second set of parameter values;

deriving a third set of weighting coefficients from the third set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time of the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values;

when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values; and

when valid data is present at the first prior reference time and the second prior reference time of the third set of parameter values and not the first set or the second set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the third set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the third set of parameter values.

24. The method of claim 16, comprising:

determining three or more additional sets of parameter values for the glucose rate-of-change estimate based on the reference glucose measurements;

wherein the three or more additional sets of parameter values point to different sets of prior reference times.

25. The method of claim 16, comprising:

determining a fourth set of parameter values for a second glucose rate-of-change estimate;

wherein the second glucose rate-of-change estimate is based on a sum of a plurality of scaled rates-of-changes;

wherein the rates-of-changes comprise;

a third rate-of-change from an alternate initial reference time to a fourth prior reference time with respect to the alternate initial reference time; and

a fourth rate-of-change from the alternate initial reference time to a fifth prior reference time with respect to the alternate initial reference time;

wherein the alternate initial reference time is prior to the initial reference time by a time delay.

26. The method of claim 15, comprising:

determining additional sets of parameter values for two or more additional glucose rate-of-change estimates;

wherein the two or more additional glucose rate-of-change estimates are based on sums of a plurality of scaled rates-of-changes;

wherein the plurality of scaled rates-of-changes for each of the two or more additional glucose rate-of-change estimates are from an alternate initial reference time to fourth and fifth prior reference times with respect to the alternate initial reference time, wherein each set of reference times for the glucose rate-of-change estimate and the additional glucose rate-of-change estimates is unique as a whole; and

wherein the alternate initial reference time is prior to the initial reference time by a time delay.

27. The method of claim 26, wherein the time delay is predetermined based on a projected duration of artifacts.

28. The method of claim 25, wherein the rates-of-changes comprise:

one or more additional rates-of-changes from the initial reference time to additional prior reference times.

29. The method of claim 28, wherein the first set of parameter values comprises:

the first scalar of the first rate-of-change;

the first prior reference time;

the second scalar of the second rate-of-change;

the second prior reference time;

additional scalars for the additional rates-of-changes; and

each of the additional prior reference times.

30. The method of claim 28, comprising:

receiving a series of uncompensated glucose measurements;

deriving weighting coefficients from the first set of parameter values; and

calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements;

wherein the lag-compensated rate-of-change measurements are calculated by applying the weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, the second prior reference time, and each of the additional prior reference times.

31. A device, comprising:

a processor, and

a memory comprising machine-executable instructions stored thereon for lag compensation of glucose level measurements, the instructions when executed cause the processor to;

receive one or more uncompensated glucose measurements prior to lag compensation; and

determine a first set of weighting coefficients from a glucose level corresponding to measurements at an initial reference time and at least two scaled rates-of-changes from the initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time; and

calculate lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the first parameter values.

32. The device of claim 31, wherein the determining of the first set of weighting coefficients comprises determining a first set of parameter values for a glucose level estimate based on one or more glucose measurements, wherein the glucose level estimate is based on a sum of:

a glucose level corresponding to measurements at an initial reference time; and

a sum of at least two scaled rates-of-changes, wherein the rates-of-changes comprise a first rate-of-change from the initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time.

33. The device of claim 32, where the instructions comprise:

instructions for calculating error metrics for a plurality of combinations of values as parameters in the glucose level estimate; and

instructions for selecting the first set of parameter values based on the calculated error metrics.

34. The device of claim 32, where the instructions comprise:

instructions for determining a second set of parameter values for the glucose level estimate based on the one or more glucose measurements;

wherein the first set and the second set of parameter values point to different sets of prior reference time.

35. The device of claim 34, where the instructions comprise:

instructions for receiving a series of uncompensated glucose measurements;

instructions for deriving a first set of weighting coefficients from the first set of parameter values; and

instructions for deriving a second set of weighting coefficients from the second set of parameter values;

instructions for, when valid data is present at the first prior reference time and the second prior reference time for the first set of parameter values, calculating lag-compensated point measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values; and

instructions for, when valid data is present at the first prior reference time and the second prior reference time for the second set of parameter values and not the first set of parameter values, calculating lag-compensated glucose level measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values.

36. The device of claim 32, where the instructions comprise:

instructions for determining a third set of parameter values for the glucose level estimate based on the one or more glucose measurements;

wherein the first, second, and third sets of parameter values point to different sets of prior reference times.

37. The device of claim 36, where the instructions comprise:

instructions for receiving a series of uncompensated glucose measurements;

instructions for deriving a first set of weighting coefficients from the first set of parameter values;

instructions for deriving a second set of weighting coefficients from the second set of parameter values;

instructions for deriving a third set of weighting coefficients from the third set of parameter values;

instructions for when valid data is present at the first prior reference time and the second prior reference time for the first set of parameter values, calculating lag-compensated point measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time for the first set of parameter values;

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated point measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values; and

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the third set of parameter values and not the first set or the second set of parameter values, calculating lag-compensated point measurements from the uncompensated glucose measurements by applying the third set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the third set of parameter values.

38. The device of claim 31, where the instructions comprise:

instructions for determining a fourth set of parameter values for a second glucose level estimate;

wherein the second glucose level estimate is based on a sum of an glucose level and a sum of a plurality of scaled rates-of-changes;

wherein the glucose level corresponds to measurements at an alternate initial reference time, wherein the alternate initial reference time is prior to the initial reference time by a time delay;

wherein the rates-of-changes comprise;

a third rate-of-change from the alternate initial reference time to a fourth prior reference time with respect to the alternate initial reference time; and

a second rate-of-change from the alternate initial reference time to a fifth prior reference time with respect to the alternate initial reference time; and

39. The device of claim 38, wherein the time delay is predetermined based on a projected duration of artifacts.

40. The device of claim 38, where the instructions comprise:

instructions for deriving a first set of weighting coefficients from the first set of parameter values;

instructions for calculating first lag-compensated point measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values;

instructions for deriving a fourth set of weighting coefficients from the fourth set of parameter values;

instructions for calculating second lag-compensated point measurements from the uncompensated glucose measurements by applying the fourth set of weighting coefficients to corresponding uncompensated glucose measurements received at the alternate initial reference time, at the fourth prior reference time, and at the fifth prior reference time of the fourth set of parameter values;

instructions for determining a severity of discrepancy between the first and the second glucose level estimates; and

instructions for generating resulting lag-compensated point measurements based on a weighted sum of the first lag compensated point measurements and the second lag-compensated point measurements, wherein the weighted sum is based on the severity of discrepancy.

41. A device, comprising:

a processor, and

a memory comprising machine-executable instructions stored thereon for lag compensation of glucose rate-of-change measurements, the instructions when executed cause the processor to;

receive a series of uncompensated glucose measurements prior to lag compensation;

determine a first set of weighting coefficients from a plurality of scaled rates-of-changes comprising a first rate-of-change from an initial reference time to a first prior reference time and a second rate-of-change from the initial reference time to a second prior reference time; and

calculate lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time, and the second prior reference time of the first set of parameter values.

42. The device of claim 41, wherein the determining of the first set of weighting coefficients comprises determining a first set of parameter values for a glucose rate-of-change estimate based on reference glucose measurements, wherein the glucose rate-of-change estimate is based on a sum of a plurality of scaled rates-of-changes.

43. The device of claim 41, wherein the determining of the first set of parameter values comprises:

instructions for calculating error metrics for a plurality of combinations of values as parameters in the glucose rate-of-change estimate; and

instructions for selecting the first set of parameter values based on the calculated error metrics.

44. The device of claim 42, wherein the instructions comprise:

instructions for determining a second set of parameter values for the glucose rate-of-change estimate based on the one or more glucose measurements;

wherein the first set and the second set of parameter values point to different sets of prior reference times.

45. The device of claim 44, wherein the instructions comprise:

instructions for receiving a series of uncompensated glucose measurements;

instructions for deriving a first set of weighting coefficients from the first set of parameter values;

instructions for deriving a second set of weighting coefficients from the second set of parameter values;

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values; and

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values.

46. The device of claim 42, wherein the instructions comprise:

instructions for determining a third set of parameter values for the glucose rate-of-change estimate based on the reference glucose measurements;

wherein the first set, second set, and third set of parameter values point to different sets of prior reference times.

47. The device of claim 46, wherein the instructions comprise:

instructions for receiving a series of uncompensated glucose measurements;

instructions for deriving a first set of weighting coefficients from the first set of parameter values;

instructions for deriving a second set of weighting coefficients from the second set of parameter values;

instructions for deriving a third set of weighting coefficients from the third set of parameter values;

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values;

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the second set of parameter values and not the first set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the second set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the second set of parameter values; and

instructions for, when valid data is present at the first prior reference time and the second prior reference time of the third set of parameter values and not the first set or the second set of parameter values, calculating lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the third set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the third set of parameter values.

48. The device of claim 42, wherein the instructions comprise:

instructions for determining a fourth set of parameter values for a second glucose rate-of-change estimate;

wherein the second glucose rate-of-change estimate is based on a sum of a plurality of scaled rates-of-changes;

wherein the rates-of-changes comprise;

a third rate-of-change from an alternate initial reference time to a fourth prior reference time with respect to the alternate initial reference time; and

a fourth rate-of-change from the alternate initial reference time to a fifth prior reference time with respect to the alternate initial reference time;

wherein the alternate initial reference time is prior to the initial reference time by a time delay.

49. The device of claim 48, wherein the time delay is predetermined based on a projected size of artifacts.

50. The device of claim 48, wherein the instructions comprise:

instructions for deriving a first set of weighting coefficients from the first set of parameter values;

instructions for calculating first lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the first set of weighting coefficients to corresponding uncompensated glucose measurements received at the initial reference time, at the first prior reference time, and at the second prior reference time of the first set of parameter values instructions for deriving a fourth set of weighting coefficients from the fourth set of parameter values;

instructions for calculating second lag-compensated rate-of-change measurements from the uncompensated glucose measurements by applying the fourth set of weighting coefficients to corresponding uncompensated glucose measurements received at the alternate initial reference time, at the fourth prior reference time, and at the fifth prior reference time of the fourth set of parameter values;

instructions for determining a severity of discrepancy between the first and the second glucose rate-of-change estimates;

instructions for generating resulting lag-compensated rate-of-change measurements based on a weighted sum of the first lag compensated rate-of-change measurements and the second lag-compensated rate-of-change measurements, wherein the weighted sum is based on the severity of discrepancy.