Sensitivity calibration of in vivo sensors used to measure analyte concentration

Abstract

Methods, devices, systems, and computer program products are provided to improve sensitivity calibration of an in vivo analyte sensor and usability of an associated analyte monitoring system. In certain embodiments, methods are provided that improve the user experience of using an analyte monitoring system. Certain embodiments of the present disclosure include features that reduce the amount of calibration or re-calibration performed by the analyte monitoring system. More specifically methods of using a suspect calibration attempt to avoid having to recalibrate by adjusting the calibration or mitigating effects of sensor signal attenuation that caused the calibration attempt to be suspect are provided. Additional features are disclosed.

What is claimed is: 
     
         1 . A method for calibrating a signal generated by a glucose sensor indicative of a glucose level of a user, comprising:
 storing a nominal sensor sensitivity for the glucose sensor, the glucose sensor having an in vivo portion configured to be positioned in contact with an interstitial fluid of the user and an ex vivo portion;   receiving a signal generated by the glucose sensor over a first time period and indicative of the glucose level of the user over the first time period;   receiving a reference blood glucose measurement of the user;   pairing the reference blood glucose measurement with the signal to form a paired data;   determining a risk distribution based on the nominal sensor sensitivity and the paired data;   adjusting a statistical property of the nominal sensor sensitivity based on the risk distribution;   after adjusting the statistical property of the nominal sensor sensitivity, calibrating the signal generated by the glucose sensor over a second time period to generate calibrated glucose level data corresponding to glucose level data using the nominal sensor sensitivity having the adjusted statistical property, the second time period being after the first time period; and   transmitting the calibrated glucose level data to a display unit.   
     
     
         2 . The method of  claim 1 , wherein the statistical property is a mean of sensitivities. 
     
     
         3 . The method of  claim 1 , wherein the statistical property is a standard deviation of sensitivities. 
     
     
         4 . The method of  claim 1 , wherein the statistical property is a median of sensitivities. 
     
     
         5 . The method of  claim 1 , wherein the nominal sensor sensitivity is determined based on statistics of a sample lot. 
     
     
         6 . The method of  claim 1 , wherein the nominal sensor sensitivity is determined based on past calibrations. 
     
     
         7 . The method of  claim 1 , further comprising determining a calibration adjustment based on the risk distribution and the nominal sensor sensitivity having an adjusted statistical property; and
 wherein calibrating the signal generated by the glucose sensor over the second time period is further based on the calibration adjustment.   
     
     
         8 . The method of  claim 7 , wherein determining the calibration adjustment is based on a continuous function. 
     
     
         9 . The method of  claim 7 , wherein determining the calibration adjustment is based on a lookup table. 
     
     
         10 . The method of  claim 1 , further comprising storing the adjustment in a non-transitory memory of a sensor electronics for the glucose sensor. 
     
     
         11 . The method of  claim 1 , wherein the nominal sensor sensitivity includes a lot sensitivity of a plurality of glucose sensors of a manufacturing lot, and the plurality of glucose sensors includes the glucose sensor. 
     
     
         12 . A glucose monitoring system, comprising:
 a glucose sensor having an in vivo portion configured to be positioned in contact with an interstitial fluid of a user and an ex vivo portion;   a non-transitory memory; and   at least one processor communicatively coupled to the non-transitory memory and the glucose sensor and configured to:
 store a nominal sensor sensitivity for the glucose sensor; 
 receive a signal generated by the glucose sensor over a first time period and indicative of a glucose level of the user over the first time period; 
 receiving a reference blood glucose measurement of the user; 
 pair the reference blood glucose measurement with the signal to form a paired data; 
 determine a risk distribution based on the nominal sensor sensitivity and the paired data; 
 adjust a statistical property of the nominal sensor sensitivity based on the risk distribution; 
 after adjusting the statistical property of the nominal sensor sensitivity, calibrate the signal generated by the glucose sensor over a second time period to generate calibrated glucose level data corresponding to glucose level data using the nominal sensor sensitivity having the adjusted statistical property, the second time period being after the first time period; and 
 transmit the calibrated glucose level data to a display unit. 
   
     
     
         13 . The system of  claim 12 , wherein the statistical property is a mean of sensitivities. 
     
     
         14 . The system of  claim 12 , wherein the statistical property is a standard deviation of sensitivities. 
     
     
         15 . The system of  claim 12 , wherein the statistical property is a median of sensitivities. 
     
     
         16 . The system of  claim 12 , wherein the nominal sensor sensitivity is determined based on statistics of a sample lot. 
     
     
         17 . The system of  claim 12 , wherein the nominal sensor sensitivity is determined based on past calibrations. 
     
     
         18 . The system of  claim 12 , further comprising determining a calibration adjustment based on the risk distribution and the nominal sensor sensitivity having an adjusted statistical property; and
 wherein calibrating the signal generated by the glucose sensor over the second time period is further based on the calibration adjustment.   
     
     
         19 . The system of  claim 18 , wherein determining the calibration adjustment is based on a continuous function. 
     
     
         20 . The system of  claim 18 , wherein determining the calibration adjustment is based on a lookup table. 
     
     
         21 . The system of  claim 12 , further comprising storing the adjustment in the non-transitory memory. 
     
     
         22 . The system of  claim 12 , wherein the nominal sensor sensitivity includes a lot sensitivity of a plurality of glucose sensors of a manufacturing lot, and the plurality of glucose sensors includes the glucose sensor.