System and method for measuring an analyte in a sample and correcting for interferents

• US 9,709,521 B2
• Filed: 03/20/2012
• Issued: 07/18/2017
• Est. Priority Date: 03/25/2011
• Status: Active Grant

• Current Assignee: LifeScan IP Holdings, LLC
• Original Assignee: Cilag Gmbh International (Johnson & Johnson)
• Inventors: Matzinger, David, Teodorczyk, Maria
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Fisher, Brittany
• Application Number:
  US14/007,234
• Publication Number:
  US 20140311924A1
• Time in Patent Office: 1,946 Days
• Field of Search: 422410
• CPC Class Codes: A61B 2562/0295 Strip shaped analyte sensors for apparatus classified in A61B5/145 or A61B5/157 disposable multilayered or laminated electrodes G01N27/307; details of handling chemical test elements G01N33/4875
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

Abstract

Methods and systems to apply a plurality of test voltages to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip so that a glucose concentration can be determined that account for interferent substances in the body fluid sample. A method of determining blood glucose concentration with a glucose measurement system that includes a test strip and test meter. The test meter has a microcontroller configured to apply a plurality of test voltages to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip.

Claims

1. A method of determining blood glucose concentration with a glucose measurement system that includes a test strip and test meter, the test meter having a microcontroller configured to apply a plurality of test voltages comprising first, second and third test voltages to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip, the method comprising:

inserting the test strip into a strip port connector of the test meter to connect at least two electrodes of the test strip to a strip measurement circuit;

initiating a test sequence after deposition of a sample by causing the first test voltage to be applied, the first test voltage causing a transformation of analytes in the sample from one form to a different form;

switching a first test voltage to a second test voltage different than the first test voltage;

changing the second test voltage to a third test voltage different from the second voltage;

measuring a second current output of the current transient from the electrodes after the changing from the second test voltage to the third test voltage;

estimating a current that approximates a steady state current output of the current transient after the third test voltage is maintained at the electrodes;

calculating a blood glucose concentration based on the first, second and third current output of the current transient with an equation of the form;

2. The method of claim 1, in which the coefficients A and B comprise approximately 1.004 and approximately 0.0077, respectively.

3. A method of determining blood glucose concentration with a glucose measurement system that includes a test strip and test meter, the test meter having a microcontroller configured to apply a plurality of test voltages comprising a first test voltage, a second test voltage, and a third test voltage to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip, the method comprising:

inserting the test strip into a strip port connector of the test meter to connect at least two electrodes of the test strip to a strip measurement circuit;

initiating a test sequence after deposition of a sample by applying the first test voltage;

causing a transformation of analytes in the sample from one form to a different form;

switching the first test voltage to a second test voltage different than the first test voltage;

changing the second test voltage to a third test voltage different from the second voltage;

measuring a second current output of the current transient from the electrodes after the changing from the second test voltage to the third test voltage;

estimating approximate steady state current output of the current transient after the third test voltage is maintained at the electrodes;

calculating a blood glucose concentration based on the first, second and third current output of the current transient with an equation of the form;

4. The method of claim 3, in which the step of switching comprises changing the polarity of the second test voltage with respect to the first test voltage.

5. The method of claim 3, in which the deriving of the first corrected glucose concentration comprises calculating with equations of the form:

6. The method of claim 3, in which the deriving of the second corrected glucose concentration comprises calculating with equations of the form

7. The method of claim 3, in which the measuring of the first current output comprises measuring a current output of the at least two electrodes at about 1.1 seconds after initiation of test sequence.

8. The method of claim 3, in which the measuring of the second current output comprises measuring a current output of the at least two electrodes at about 4.1 seconds after initiation of test sequence.

9. The method of claim 3, in which the estimating of the steady state current output comprises measuring a current output of the at least two electrodes at about 5 seconds after initiation of test sequence.

10. The method of claim 3, in which the coefficients A, B, C, D, and E comprise approximately 1.004, approximately 0.0077, approximately 0.889, approximately 0.0220 and approximately −

0.00036, respectively.

11. The method of claim 5, in which the coefficients A and B comprise approximately 1.004 and approximately 0.0077, respectively.

12. The method of claim 5, in which the coefficients C, D, and E comprise approximately 0.889, approximately 0.0220 and approximately −

0.00036, respectively.

13. The method of claim 5, in which the manufacturing parameter a comprises approximately 0.192, b comprises approximately 0.68, c comprises approximately 2, p comprises approximately 0.52, and zgr comprises approximately 2.

14. The method of claim 3, in which the threshold percentage is greater than 10% difference in glucose concentrations.

15. A blood glucose measurement system comprising:

an analyte test strip including;

a substrate having a reagent disposed thereon;

at least two electrodes proximate the reagent in test chamber;

an analyte meter including;

a strip port connector disposed to connect to the two electrodes;

a power supply; and

a microcontroller electrically coupled to the strip port connector and the power supply, the microcontroller programmed to,

apply a first test voltage;

switch the first test voltage to a second test voltage different than the first test voltage;

change the second test voltage to a third test voltage different from the second test voltage,

measure a second current output of the current transient from the electrodes after the change from the second test voltage to the third test voltage,

estimate a current that approximates a steady state current output of the current transient after the third test voltage is maintained at the electrodes, and

determine a glucose concentration G₁ and a corrected glucose concentration G_corr to account for interfering agents so that at least 97% of corrected test results are within respective bias criterion of ±

10 mg/dL at 65 mg/dL, 240 mg/dL, or at 450 mg/dL as compared to reference YSI data;

±

12 mg/dL at 65 mg/dL, 240 mg/dL, or 450 mg/dL as compared to reference YSI data; and

±

15 mg/dL at 65 mg/dL, 240 mg/dL, or 450 mg/dL as compared to reference YSI data, the glucose concentration and the corrected glucose concentration based on the first, second and third current output and being derived from the following equations;

16. The system of claim 15, in which the manufacturing parameters a, b, c, p, zgr are such that a comprises approximately 0.192, b comprises approximately 0.68, c comprises approximately 2, p comprises approximately 0.52 and zgr comprises approximately 2.

17. The system of claim 15, in which the coefficients C, D, and E comprise approximately 0.889, approximately 0.0220 and approximately −

0.00036, respectively.