System and methods for processing analyte sensor data for sensor calibration
Systems and methods for processing sensor analyte data are disclosed, including initiating calibration, updating calibration, evaluating clinical acceptability of reference and sensor analyte data, and evaluating the quality of sensor calibration. The sensor can be calibrated using a calibration set of one or more matched sensor and reference analyte data pairs. Reference data resulting from benchtop testing an analyte sensor prior to its insertion can be used to provide initial calibration of the sensor data. Reference data from a short term continuous analyte sensor implanted in a user can be used to initially calibrate or update sensor data from a long term continuous analyte sensor.
1. A method for making a transcutaneous analyte sensor system, the method comprising:
determining slopes or baselines for a set of transcutaneous analyte sensors;
determining a conversion function for calibrating data acquired from at least one other transcutaneous analyte sensor, wherein the conversion function comprises a slope or a baseline, wherein the slope is representative of a sensor sensitivity, and wherein the slope or the baseline of the conversion function of the at least one other transcutaneous analyte sensor is determined based at least in part on distribution information for the determined slopes or baselines for the set of transcutaneous analyte sensors; and
storing the conversion function in a memory of the transcutaneous analyte sensor system, wherein the conversion function eliminates the dependency of calibration on reference analyte values obtained by the host.
2. The method of claim 1 , wherein determining the conversion function comprises determining the slope based on prior slope distribution information.
3. The method of claim 2 , wherein determining the slope comprises selecting a most probable slope from a distribution of slopes based on the prior slope distribution information.
4. The method of claim 1 , wherein determining the conversion function comprises determining the baseline based on prior baseline distribution information.
5. The method of claim 4 , wherein determining the baseline comprises selecting a most probable baseline from a distribution of baselines based on the prior baseline distribution information.
6. The method of claim 1 , wherein determining the conversion function comprises determining the slope and the baseline based on prior slope and baseline distribution information.
7. The method of claim 6 , wherein determining the slope and the baseline comprises selecting a most probable slope and baseline from a distribution of slopes and baselines based on the prior slope and baseline distribution information.
8. The method of claim 7 , wherein selecting the most probable slope and baseline comprises selecting a slope and baseline closest to the maximum joint probability of both the slope and baseline distributions.
9. The method of claim 1 , where determining the conversion function comprises selecting one of a plurality of possible calibration lines having various baselines and slopes based on prior information indicative of a typical distribution of slopes and/or baselines.
10. The method of claim 1 , wherein the slope is determined, at least in part, based on in-vitro slope information determined by a benchtop calibration process.
11. The method of claim 1 , wherein the prior distribution information is derived from in vivo testing of at least one other transcutaneous analyte sensor or in vitro testing.
12. The method of claim 1 , wherein the analyte is glucose.
13. The method of claim 1 , wherein the distribution information comprises normal distributions.
14. The method of claim 1 , wherein the slope of the conversion function is determined based at least in part on corrections for a difference between an in vivo sensor sensitivity and an in vitro sensor sensitivity.