Transcutaneous analyte sensor
The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous measurement of glucose in a host.
1. A system for monitoring glucose concentration in a host, the system comprising:
a substantially continuous glucose sensor configured to produce sensor data indicative of a glucose concentration in a host; and
a receiver configured to receive the sensor data from the substantially continuous glucose sensor and receive reference data from an in vitro single point glucose monitor, the reference data indicative of a measured glucose concentration in a biological sample from the host, wherein the receiver comprises:
a processor module; and
a computer readable memory comprising:
instructions configured to cause the processor module to determine a rate of change of the glucose concentration in the host at a time corresponding to the measured glucose concentration in the biological sample;
instructions configured to determine whether the rate of change is within a range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans;
instructions configured to cause the processor module to calibrate the sensor data, wherein the instructions are configured to allow the processor module to calibrate the sensor data using the reference data when the rate of change is within the range, but not allow the processor module to calibrate the sensor data using the reference data when the rate of change is outside the range
instructions configured to cause the processor module to determine a time lag between the sensor data and the reference data based at least in part on the determined rate of change; and
instructions configured to cause the processor module to form a matched data pair by matching one or more sensor data points of the sensor data with one or more data points of the reference data using the determined time lag,
wherein calibrating the sensor data is based at least in part on the matched data pair.
2. The system of claim 1 , wherein the maximum normally sustainable rates of change of glucose in humans is outside a range of +/−4 mg/dL/min.
3. The system of claim 1 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions for prospective calibration.
4. The system of claim 1 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate during initialization of the continuous glucose sensor.
5. The system of claim 1 , wherein the instructions configured to cause the processor module to calibrate the glucose data comprise instructions configured to calibrate after initialization of the continuous glucose sensor.
6. The system of claim 1 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate the sensor data based on reference data indicative of a single glucose concentration measured by the in vitro single point glucose monitor.
7. The system of claim 1 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate the sensor data based on reference data indicative of more than one glucose concentration measured by the in vitro single point glucose monitor.
8. The system of claim 1 , wherein the computer readable memory further comprises instructions configured to cause the processor module to filter the sensor data.
9. The system of claim 8 , wherein the instructions configured to filter the sensor data are further configured to cause the processor module to adaptively filter the sensor data.
10. The system of claim 9 , wherein the instructions configured to adaptively filter the sensor data are configured to cause the processor module to adaptively filter the sensor data based on a detection of signal artifacts.
11. The system of claim 9 , wherein the instructions configured to adaptively filter the sensor data are configured to cause the processor module to adaptively filter the sensor data based on the rate of change of the calibrated sensor data.
12. The system of claim 8 , wherein the instructions configured to calculate a rate of change are configured to cause the processor module to calculate a rate of change based on the filtered sensor data.
13. The system of claim 1 , wherein the in vitro glucose monitor is integrated with the receiver.
14. A system for monitoring glucose concentration in a host, the system comprising:
a substantially continuous glucose sensor configured to produce sensor data indicative of a glucose concentration in a host;
a communications module configured to receive the sensor data from the substantially continuous glucose sensor and receive reference data from an in vitro single point glucose monitor, the in vitro single point glucose monitor configured to receive a biological sample from the host and to measure a glucose concentration in the sample, wherein the reference data is indicative of the measured glucose concentration in the sample;
a processor module; and
a computer readable memory comprising instructions that, when executed by the processor module, are configured to cause the processor module to:
calibrate the sensor data received from the substantially continuous glucose sensor;
determine a rate of change of the calibrated sensor data;
not calibrate the sensor data using the glucose concentration measured by the single point glucose monitor when the rate of change of the calibrated sensor data is outside of a range of +/−4 mg/dL/min; and
determine a time lag between the sensor data and the glucose concentration measured by the in vitro single point glucose monitor using at least the determined rate of change,
wherein calibrating the sensor data comprises compensating for the time lag.
15. The system of claim 14 , wherein the range is +/−5 mg/dL/min.
16. The system of claim 14 , wherein the range is +/−6 mg/dL/min.
17. The system of claim 14 , wherein the reference data includes a time stamp of the glucose concentration measured by the in vitro single point glucose monitor.
18. The system of claim 14 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions for prospective calibration.
19. The system of claim 14 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate during initialization of the continuous glucose sensor.
20. The system of claim 14 , wherein the instructions configured to cause the processor module to calibrate the glucose data comprise instructions configured to calibrate after initialization of the continuous glucose sensor.
21. The system of claim 14 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate the sensor data based on a single glucose concentration measured by the in vitro single point glucose monitor.
22. The system of claim 14 , wherein the instructions configured to cause the processor module to calibrate the sensor data comprise instructions configured to calibrate the sensor data based on more than one glucose concentration measured by the in vitro single point glucose monitor.
23. The system of claim 14 , wherein the instructions are further configured to cause the processor module to filter the sensor data.
24. The system of claim 23 , wherein the instructions configured to filter the sensor data are further configured to adaptively filter the sensor data.
25. The system of claim 24 , wherein the instructions configured to adaptively filter the sensor data are configured to adaptively filter the sensor data based on a detection of signal artifacts.
26. The system of claim 24 , wherein the instructions configured to adaptively filter the sensor data are configured to adaptively filter the sensor data based on the rate of change of the calibrated sensor data.
27. The system of claim 23 , wherein the instructions configured to calculate a rate of change are configured to calculate a rate of change based on the filtered sensor data.
28. The system of claim 14 , wherein the communication module, the processor module and the instructions are incorporated into a receiver device.
29. The system of claim 28 , wherein the in vitro single point glucose monitor is integral with the receiver device.