Method and apparatus for analyte measurements using calibration sets

Abstract

Examples of methods and apparatus are described that permit an analyte concentration to be estimated from a measurement in the presence of compounds that interfere with the measurement. In one example, the method can reduce the error in the estimation of analyte concentration in the presence of interferents. The method can include the use of one or more calibration set to determine analyte concentration. From a sample measurement, each calibration set can be tested to determine if it is eligible to estimate the analyte concentration in the sample. An estimate of analyte concentration can then be produced, based at least in part on the eligible calibration sets and on the sample measurement. In some implementations, if no calibration sets are eligible, an action is taken such as not outputting an estimate, displaying an alarm or alert, or providing a notification.

1 . A method for estimating a concentration of an analyte in a sample, the method comprising:
 receiving one or more calibration sets, each calibration set usable to estimate an analyte concentration for a sample;   accessing a measurement of the sample;   processing the measurement of the sample to reduce or minimize effects on the estimate of concentration of the analyte caused by one or more interferents;   determining, for each of the one or more calibration sets, whether the calibration set is eligible to estimate analyte concentration from the processed measurement of the sample; and   determining, via execution of instructions by a computing system comprising computing hardware, an estimated analyte concentration for the sample based at least in part on the processed measurement of the sample and the calibration sets determined to be eligible.   
     
     
         2 . The method of  claim 1 , wherein the one or more calibration sets comprise a plurality of calibration sets. 
     
     
         3 . The method of  claim 1 , wherein the sample includes at least one component of blood, and wherein the analyte comprises glucose. 
     
     
         4 . The method of  claim 1 , wherein the accessing a measurement of the sample further comprises:
 accessing a raw measurement of the sample; and   calculating a measurement of the sample based at least in part on the raw measurement of the sample.   
     
     
         5 . The method of  claim 1 , wherein the measurement of a sample comprises a measured spectrum. 
     
     
         6 . The method of  claim 5 , wherein each of the one or more calibration sets comprises data usable to estimate an analyte concentration and a reconstructed spectrum from at least the measured spectrum. 
     
     
         7 . The method of  claim 6 , wherein determining whether the calibration set is eligible to estimate analyte concentration further comprises:
 calculating, for each of the one or more calibration sets, a reconstructed spectrum based at least in part on the measured spectrum and the calibration set; and   comparing the reconstructed spectrum to the measured spectrum.   
     
     
         8 . The method of  claim 7 , wherein each of the one or more calibration sets further comprises a prediction eligibility threshold, and wherein comparing the reconstructed spectrum to the measured spectrum comprises:
 calculating a distance metric based at least on the reconstructed spectrum and the measured spectrum, and   comparing the distance metric to the prediction eligibility threshold to determine whether the calibration set is eligible to estimate analyte concentration.   
     
     
         9 . The method of  claim 8 , wherein the distance metric is calculated, at least in part, by a sum of a square of the residuals according to the formula: 
       
         
           
             
               
                 M 
                 m 
               
               = 
               
                 
                   ∑ 
                   
                     i 
                     = 
                     1 
                   
                   n 
                 
                  
                 
                   
                     ( 
                     
                       
                         
                           R 
                           m 
                         
                          
                         
                           ( 
                           
                             λ 
                             i 
                           
                           ) 
                         
                       
                       - 
                       
                         
                           C 
                           s 
                         
                          
                         
                           ( 
                           
                             λ 
                             i 
                           
                           ) 
                         
                       
                     
                     ) 
                   
                   2 
                 
               
             
           
         
         where M m  is the distance metric for an mth calibration set, R m (λ i ) is a value of a reconstructed spectrum for the mth calibration set at an ith wavelength, C s (λ i ) is a value of the measured spectrum at the ith wavelength, and where there are n wavelengths in both the reconstructed spectrum for the mth calibration set and the measured spectrum. 
       
     
     
         10 . The method of  claim 1 , wherein the method will not determine an estimated analyte concentration if none of the plurality of calibration sets are eligible to estimate analyte concentration from the measurement of the sample. 
     
     
         11 . The method of  claim 10 , further comprising:
 if one or more of the calibration sets are determined to be eligible:
 returning the estimated analyte concentration for the sample to a display system; 
   if none of the plurality of calibration sets are determined to be eligible:
 returning a no read indication to the display system. 
   
     
     
         12 . The method of  claim 1 , wherein determining an estimated analyte concentration for the sample comprises:
 calculating, for each of the eligible calibration sets, an estimate of analyte concentration based at least in part on the measurement of the sample and the calibration set;   determining an estimated analyte concentration for the sample by combining the estimates of analyte concentrations for each of the eligible calibration sets.   
     
     
         13 . The method of  claim 12 , wherein combining the estimated analyte concentrations for each of the eligible calibration sets comprises using a weighted average to combine the estimated analyte concentrations for each of the eligible calibration sets. 
     
     
         14 . The method of  claim 13 , wherein the weighted average is calculated, at least in part, by assigning a greater to weight to estimates of analyte concentration that are either above or below a predetermined threshold level. 
     
     
         15 . The method of  claim 14 , wherein the analyte is glucose and the predetermined threshold level is 100 mg/dL. 
     
     
         16 . The method of  claim 1 , wherein processing the measurement of the sample to reduce or minimize effects on the estimate of concentration of the analyte caused by one or more interferents comprises correcting for the presence of water or saline in the measurement. 
     
     
         17 . The method of  claim 16 , wherein the processing further comprises correcting the measurement for the presence of a protein or a drug that may be present in the sample. 
     
     
         18 . The method of  claim 1 , wherein processing the measurement of the sample to reduce or minimize effects on the estimate of concentration of the analyte caused be one or more interferents comprises receiving information on substances likely to be present in the sample, and correcting the measurement for at least some of the substances likely to be present in the sample. 
     
     
         19 . The method of  claim 18 , further comprising determining which potential interferents are to be processed in the measurement. 
     
     
         20 . The method of  claim 19 , wherein determining which potential interferents are to be processed comprises determining whether a potential interferent is present in the measurement above a threshold level. 
     
     
         21 - 39 . (canceled)