System and methods for processing analyte sensor data

• US 7,797,028 B2
• Filed: 04/14/2008
• Issued: 09/14/2010
• Est. Priority Date: 08/01/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Goode, Paul V. Jr., Brauker, James H., Carr-Brendel, Victoria, Kamath, Apurv U.
• Primary Examiner(s): Nasser; Robert L
• APPLICATION: US 20080194936A1
• Time in patent office: 883 Days
• Field of Search: None
• US Class Current: 600/347
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/04 Constructional details of apparatus
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/1433 provided with locking means details of syringes A61M5/315
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1468 using chemical or electrochemical methods, e.g. by polarographic means A61B5/1486 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: G01N 33/48707 by electrical means G01N33/49, G01N33/493 take precedence
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

Systems and methods for processing sensor analyte data, including initiating calibration, updating calibration, evaluating clinical acceptability of reference and sensor analyte data, and evaluating the quality of sensor calibration. During initial calibration, the analyte sensor data is evaluated over a period of time to determine stability of the sensor. The sensor may be calibrated using a calibration set of one or more matched sensor and reference analyte data pairs. The calibration may be updated after evaluating the calibration set for best calibration based on inclusion criteria with newly received reference analyte data. Fail-safe mechanisms are provided based on clinical acceptability of reference and analyte data and quality of sensor calibration. Algorithms provide for optimized prospective and retrospective analysis of estimated blood analyte data from an analyte sensor.

Claims

1. A method for determining a stability of a continuous glucose sensor, the method comprising:

receiving a data stream from a continuous glucose sensor, including a signal associated with a glucose concentration in a host and a signal associated with interfering species in the host; and

determining a level of stability of the continuous glucose sensor by evaluating the signal associated with interfering species in the host to detect a baseline drift or a baseline offset using a processor module, wherein the determining a level of stability is performed in real-time.

2. The method of claim 1, wherein the determining a level of stability comprises comparing the signal associated with a glucose concentration to a template.

3. The method of claim 1, wherein the determining a level of stability comprises monitoring a frequency content of the signal associated with a glucose concentration over a predetermined amount of time.

4. The method of claim 1, wherein the determining a level of stability of the continuous glucose sensor comprises evaluating pH, oxygen, hypochlorite, correlation of matched pairs, R-value, and/or an amplitude associated with the data stream.

5. The method of claim 1, further comprising providing output responsive to the level of stability of the continuous glucose sensor, wherein the output is audible, visual, tactile, and/or a wireless transmission.

6. The method of claim 5, wherein the providing output comprises at least one of a numeric, a directional trend, or a graphical representation associated with the glucose concentration of the host.

7. The method of claim 5, wherein providing output comprises alerting a user of a present and/or upcoming hypoglycemic and/or hyperglycemic event.

8. The method of claim 5, wherein providing output comprises sending at least one of a numeric value or a rate of change associated with the glucose concentration of the host to an insulin pump.

9. The method of claim 8, wherein sending at least one of a numerical value or a rate of change value associated with the glucose concentration of the host to an insulin pump occurs only when a predetermined level of stability is determined.

10. The method of claim 1, further comprising receiving reference data from a reference glucose monitor, the reference data including one or more reference data points, and wherein the receiving reference data comprises receiving reference data from a blood glucose test.

11. The method of claim 1, further comprising receiving reference data from a reference glucose monitor, the reference data including one or more reference data points, and wherein the receiving reference data from a reference glucose monitor comprises receiving, within a receiver, an internal communication from a reference glucose monitor integral with the receiver.

12. The method of claim 1, wherein determining a level of stability of the continuous glucose sensor further comprises evaluating a sensitivity associated with the continuous glucose sensor.

13. The method of claim 12, wherein evaluating a sensitivity comprises evaluating an amplitude of the sensitivity or variability of the sensitivity.

14. The method of claim 1, wherein determining a stability of the continuous glucose sensor comprises determining a physiological stability of host tissue surrounding the continuous glucose sensor when subcutaneously implanted in the host.

15. The method of claim 1, wherein determining a level of stability of the continuous glucose sensor is based at least in part on environmental information provided by the host.

16. A system for determining a stability of a continuous glucose sensor, comprising:

a sensor data module operatively connected to a continuous glucose sensor and configured to receive a data stream comprising a signal associated with a glucose concentration in a host and a signal associated with interfering species in the host; and

a processor module programmed to determine a level of stability of the continuous glucose sensor in real-time by evaluating the signal associated with interfering species in the host to detect a baseline drift or a baseline offset.

17. The system of claim 16, wherein the processor module is configured to determine the level of stability based on a comparison of the signal associated with a glucose concentration in the host with a template.

18. The system of claim 16, wherein the processor module is configured to determine a level of stability by monitoring a frequency content of the signal associated with a glucose concentration in the host over a predetermined amount of time.

19. The system of claim 16, wherein the processor module is further programmed to evaluate pH, oxygen, hypochlorite, correlation of matched pairs, R-value, and/or an amplitude associated with the data stream.

20. The system of claim 16, further comprising an output module associated with the processor module and programmed to control output of sensor data responsive to the level of stability of the continuous glucose sensor.

21. The system of claim 20, wherein the output module is configured to alert a user of a present and/or upcoming hypoglycemic and/or hyperglycemic event.

22. The system of claim 20, wherein the output module provides at least one of a numeric, a directional trend, or a graphical representation associated with the glucose concentration of the host.

23. The system of claim 20, wherein the output module is configured to send at least one of a numerical value or a rate of change value associated with the glucose concentration of the host to an insulin pump.

24. The system of claim 23, wherein the output module is configured to send the at least one of a numerical value or a rate of change value associated with the glucose concentration of the host to the insulin pump only when a predetermined level of stability is determined.

25. The system of claim 16, further comprising a reference input module configured to receive reference data from a blood glucose test, wherein the reference data comprises one or more reference data points.

26. The system of claim 16, further comprising a reference glucose monitor physically connected to the system, and wherein the system further comprises a reference input module configured to receive an internal communication from the reference glucose monitor, wherein the internal communication comprises one or more reference data points.

27. The system of claim 16, wherein the processor module is configured to determine a level of stability by evaluating a sensitivity associated with the continuous glucose sensor.

28. The system of claim 27, wherein the processor module is configured to evaluate an amplitude of the sensitivity and/or variability of the sensitivity.

29. The system of claim 16, wherein the processor module is configured to determine a level of stability by evaluating a physiological stability of host tissue surrounding the continuous glucose sensor when subcutaneously implanted in the host.

30. The system of claim 16, wherein the processor module is configured to determine a level of stability by obtaining environmental information from the host.