Method Of Calibrating An Analyte-Measurement Device, And Associated Methods, Devices And Systems

Abstract

The invention relates to a method for calibrating an analyte-measurement device that is used to evaluate a concentration of analyte in bodily fluid at or from a measurement site in a body. The method involves measuring a concentration, or calibration concentration, of an analyte in blood from an “off-finger” calibration site, and calibrating the analyte-measurement device based on that calibration concentration. The invention also relates to a device, system, or kit for measuring a concentration of an analyte in a body, which employs a calibration device for adjusting analyte concentration measured in bodily fluid based on an analyte concentration measured in blood from an “off-finger” calibration site.

1 . (canceled) 
     
     
         2 . A system for monitoring analyte concentration in a biological sample of a host, the system comprising:
 a substantially continuous analyte sensor configured to produce a data signal indicative of an analyte concentration in a host during exposure of the sensor to a biological sample;   a reference solution, wherein the system is configured to expose the sensor to the reference solution, and wherein the system is configured to produce a data signal indicative of an analyte concentration in the reference solution during exposure of the sensor to the reference solution; and   a computer system comprising programming configured to determine calibration information and to calibrate a signal associated with a biological sample therefrom, wherein the calibration information comprises steady state information and transient information.   
     
     
         3 . The system of  claim 2 , wherein the reference solution has a known analyte concentration. 
     
     
         4 . The system of  claim 2 , wherein the calibration information is determined from a signal associated with exposure of the sensor to the reference solution and a signal associated with exposure of the sensor to the biological sample. 
     
     
         5 . The system of  claim 2 , wherein the steady state information comprises at least one of sensitivity information and baseline information. 
     
     
         6 . The system of  claim 5 , wherein the steady state information comprises sensitivity information and baseline information. 
     
     
         7 . The system of  claim 2 , wherein steady state information comprises information associated with a signal produced during exposure of the sensor to the reference solution. 
     
     
         8 . The system of  claim 7 , wherein the reference solution comprises a known analyte concentration of about zero, and wherein the steady state information comprises baseline information about the sensor in the reference solution. 
     
     
         9 . The system of  claim 7 , wherein the reference solution comprises a known analyte concentration of more than zero, and wherein the steady state information comprises sensitivity information about the sensor. 
     
     
         10 . The system of  claim 2 , wherein the steady state calibration information comprises reference data from an analyte sensor other than the substantially continuous analyte sensor. 
     
     
         11 . The system of  claim 2 , wherein transient information comprises a rate of change of a signal produced during exposure of the sensor to a step change in analyte concentration. 
     
     
         12 . The system of  claim 11 , wherein the rate of change comprises a rate change of a signal produced during exposure of the sensor to a biological sample of an unknown analyte concentration or an uncalibrated analyte concentration. 
     
     
         13 . The system of  claim 11 , wherein the rate of change comprises a rate change of a signal produced during exposure of the sensor to a biological sample, and wherein steady state information comprises reference data from an analyte sensor other than the substantially continuous analyte sensor. 
     
     
         14 . The system of  claim 2 , wherein transient information comprises response of a signal produced during exposure of the sensor to a change in analyte concentration. 
     
     
         15 . The system of  claim 14  wherein the response includes an impulse response, and the change in analyte concentration includes a step change in analyte concentration. 
     
     
         16 . The system of  claim 14 , wherein the response is used to determine an offset between a baseline measurement associated with the reference solution and a baseline measurement associated with a biological sample. 
     
     
         17 . The system of  claim 14 , wherein the response is used to determine a time point of a steady state measurement during which an analyte concentration can be obtained. 
     
     
         18 . The system of  claim 2 , wherein the transient information comprises a comparison of steady state information and transient information for a plurality of time spaced signals associated with biological samples of unknown analyte concentration or uncalibrated analyte concentration. 
     
     
         19 . The system of  claim 18 , wherein the comparison of steady state information and transient information is used to determine an offset between a baseline measurement associated with the reference solution and a baseline measurement associated with a biological sample. 
     
     
         20 . The system of  claim 18 , further comprising programming to detect a shift in baseline or sensitivity based on a comparison of steady state information and transient information. 
     
     
         21 . The system of  claim 20 , further comprising programming configured to initiate calibration of the signal to correct for a shift in at least one of baseline and sensitivity based on a comparison of steady state information and transient information. 
     
     
         22 . The system of  claim 20 , further comprising programming configured to calibrate of the signal to correct for a shift in at least one of baseline and sensitivity based on a comparison of steady state information and transient information. 
     
     
         23 . The system of  claim 2 , wherein the programming is configured to calibrate a signal is configured to perform at least one of initial calibration and update calibration. 
     
     
         24 . The system of  claim 2 , wherein the analyte sensor is a glucose sensor. 
     
     
         25 . A system for monitoring analyte concentration in a biological sample of a host, the system comprising:
 a substantially continuous analyte sensor configured to produce a data signal indicative of an analyte concentration in a host during exposure of the sensor to a biological sample;   a reference solution, wherein the system is configured to expose the sensor to the reference solution, and wherein the system is configured to produce a data signal indicative of an analyte concentration in the reference solution during exposure of the sensor to the reference solution; and   a computer system comprising programming configured to determine calibration information and to calibrate a signal associated with a biological sample therefrom, wherein the calibration information is determined from a signal associated with exposure of the sensor to the reference solution and a signal associated with exposure of the sensor a biological sample, wherein the biological sample is of unknown analyte concentration or uncalibrated analyte concentration.   
     
     
         26 . The system of  claim 25 , wherein the reference solution has a known analyte concentration. 
     
     
         27 . The system of  claim 25 , wherein calibration information comprises steady state information and transient information 
     
     
         28 . The system of  claim 25 , wherein steady state information comprises at least one of sensitivity information and baseline information 
     
     
         29 . The system of  claim 25 , wherein transient information comprises a rate of change of the sensor's signal responsive to exposure of the sensor to a change in analyte concentration 
     
     
         30 . The system of  claim 25 , wherein transient information comprises a rate of change of a signal produced during exposure of the sensor to a step change in analyte concentration. 
     
     
         31 . The system of  claim 25 , wherein the analyte sensor is a glucose sensor. 
     
     
         32 . A system for monitoring analyte concentration in a biological sample of a host, the system comprising:
 a substantially continuous analyte sensor configured to produce a data signal indicative of an analyte concentration in a host during exposure of the sensor to a biological sample;   a reference solution, wherein the system is configured to expose the sensor to the reference solution, and wherein the system is configured to produce a data signal indicative of an analyte concentration in the reference solution during exposure of the sensor to the reference solution; and   a computer system comprising programming configured to determine calibration information and calibrate a signal associated with a biological sample therefrom, wherein the calibration information is determined from at least one of a signal associated with exposure of the sensor to the reference solution and a signal associated with exposure of the sensor to a biological sample, wherein the biological sample is of unknown analyte concentration or uncalibrated analyte concentration.   
     
     
         33 . The system of  claim 32 , wherein the reference solution has a known analyte concentration. 
     
     
         34 . The system of  claim 32 , wherein the computer system further comprises programming configured to diagnose a condition of at least one of the sensor and the host responsive to calibration information. 
     
     
         35 . The system of  claim 32 , wherein calibration information comprises baseline information, and wherein the system comprises programming configured to determine an offset between a baseline associated with a reference solution and a baseline associated with a biological sample. 
     
     
         36 . The system of  claim 35 , wherein the offset is determined by processing an impulse response of the sensor's signal during exposure of the sensor to a step change in analyte concentration. 
     
     
         37 . The system of  claim 35 , wherein the offset is determined by a comparison of steady state information and transient information for a plurality of time spaced samples of a biological sample of unknown analyte concentration or uncalibrated analyte concentration. 
     
     
         38 . The system of  claim 35 , wherein the computer system further comprises programming configured to detect an interfering species. 
     
     
         39 . The system of  claim 38  wherein the interfering species is responsive to a change in the offset above a predetermined amount. 
     
     
         40 . The system of  claim 35 , wherein the computer system further comprises programming configured to diagnose a condition of the host's metabolic processes responsive to a change in the offset above a predetermined amount. 
     
     
         41 . The system of  claim 40 , wherein the computer system further comprises programming configured to display or transmit a message associated with the host's condition responsive to diagnosing the condition. 
     
     
         42 . The system of  claim 35 , wherein the computer system further comprises programming configured to diagnose an error and fail safe responsive to a change in the offset above a predetermined amount. 
     
     
         43 . The system of  claim 35 , wherein the computer system further comprises programming configured to recalibrate the sensor responsive to a change in the offset above a predetermined amount. 
     
     
         44 . The system of  claim 32 , wherein calibration information comprises sensitivity information, and wherein the system comprises programming configured to diagnose an error responsive to a change in sensitivity above a predetermined amount. 
     
     
         45 . The system of  claim 32 , wherein the computer system further comprises programming configured to calculate an response of a signal produced during exposure of the sensor to a change in analyte concentration, and wherein a time constant for the change is determined from the time of the peak response. 
     
     
         46 . The system of  claim 45  wherein the response of the signal includes an impulse response. 
     
     
         47 . The system of  claim 45  wherein the change in analyte concentration includes a step change. 
     
     
         48 . The system of  claim 45  wherein the time constant for the change includes a time constant for a step change. 
     
     
         49 . The system of  claim 45  wherein the time of the peak response includes the time of the peak impulse response. 
     
     
         50 . The system of  claim 45 , wherein the step of calculating an response is repeated more than one time, and wherein the computer system further comprises programming configured to diagnose a sensor condition or error responsive to a change in the time constants associated with the plurality of step changes above a predetermined threshold.