System and method for measuring an analyte in a sample

• US 8,551,320 B2
• Filed: 05/13/2009
• Issued: 10/08/2013
• Est. Priority Date: 06/09/2008
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Hodges, Alastair M., Chatelier, Ronald C.
• Primary Examiner(s): Barton, Jeffrey T
• Assistant Examiner(s): RUFO, LOUIS J
• Application Number:
  US12/464,935
• Publication Number:
  US 20090301899A1
• Time in Patent Office: 1,609 Days
• Field of Search: 205/775
• US Class Current: 205/775
• 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 for calculating an analyte concentration of a sample are provided. In one exemplary embodiment the method includes steps that are directed toward accounting for inaccuracies that occur as a result of temperature variations in a sample, a meter, or the surrounding environment. In another exemplary embodiment the method includes steps that are directed toward determining whether an adequate sample is provided in a meter because insufficient samples can result in inaccuracies. The methods that are provided can be incorporated into a variety of mechanisms, but they are primarily directed toward glucose meters for blood samples and toward meters for controls solutions.

Claims

1. A method for measuring a temperature corrected glucose concentration over a temperature range, the method comprising the steps of:

applying in a test meter a first test voltage for a first time between a first electrode and a second electrode in communication with a sample disposed on a test strip within the test meter, the first time interval being sufficient to oxidize a reduced mediator at the second electrode;

following the application of the first test voltage, applying a second test voltage for a second time interval between the first electrode and the second electrode sufficient to oxidize the reduced mediator at the first electrode;

calculating a first glucose concentration based on test current values during the first time interval and the second time interval;

measuring a temperature value using a temperature reading device incorporated into the test meter that receives the test strip; and

calculating a temperature corrected glucose concentration based on the first glucose concentration and the temperature value, wherein the step of calculating the temperature corrected concentration includes the additional steps of;

calculating a correction value based on the temperature value and the first glucose concentration; and

calculating a temperature corrected concentration based on the first glucose concentration and the correction value, wherein the correction value is calculated with a first function if the temperature value is greater than a first temperature threshold, and wherein the correction value is calculated with a second function if the temperature value is not greater than a first temperature threshold, and in which the first function is a first equation, the first equation being;

Corr₂=−

K₁(T−

T_RT)+K₂×

G₁(T−

T_RT)

Where Corr₂ is the correction value, K₁ is a first constant, T is a temperature value, T_RT is a room temperature value, K₂ is a second constant and G₁ is the first glucose concentration.

2. The method of claim 1, in which the correction value is about zero when the temperature value is about equal to room temperature value.

3. The method of claim 2, in which the room temperature is about 22 degrees Celsius.

4. The method of claim 1, further comprising the additional steps of:

determining whether the applied sample is a control solution; and

calculating the correction value with a third function if the applied sample is control solution.

9. The method of claim 1 or 5, in which the step of calculating the temperature corrected concentration further comprises:

adding the correction value to the first glucose concentration to give the temperature corrected concentration if the first glucose concentration is less than a glucose threshold.

10. The method of claim 1 or 5, in which the step of calculating the temperature corrected concentration further comprises:

dividing the correction value by one hundred and adding one to give an intermediate term; and

multiplying the intermediate term times the first glucose concentration to give a temperature corrected concentration.

11. The method of claim 1 or 5 that further comprises the following step,

determining if the correction value is greater than a threshold value, then setting the correction value to the threshold value, where the threshold value is about ten.

5. A method for measuring a temperature corrected glucose concentration over a temperature range, the method comprising the steps of:

applying in a test meter a first test voltage for a first time between a first electrode and a second electrode in communication with a sample disposed on a test strip within the test meter, the first time interval being sufficient to oxidize a reduced mediator at the second electrode;

following the application of the first test voltage, applying a second test voltage for a second time interval between the first electrode and the second electrode sufficient to oxidize the reduced mediator at the first electrode;

calculating a first glucose concentration based on test current values during the first time interval and the second time interval;

measuring a temperature value using a temperature reading device incorporated into the test meter that receives the test strip; and

calculating a temperature corrected glucose concentration based on the first glucose concentration and the temperature value, wherein the step of calculating the temperature corrected concentration includes the additional steps of;

calculating a correction value based on the temperature value and the first glucose concentration; and

calculating a temperature corrected concentration based on the first glucose concentration and the correction value, wherein the correction value is calculated with a first function if the temperature value is greater than a first temperature threshold, and wherein the correction value is calculated with a second function if the temperature value is not greater than a first temperature threshold, and in which the second function is a second equation, the second equation being;

Corr₂=−

K₃(T−

T_RT)+K₄×

G₁(T−

T_RT)+K₅×

G₁(T−

T₁)+K₆×

G₁(T−

T₁)

where Corr₂ is the correction value, K₃ is a third constant, T is a temperature value, T_RT is a room temperature value, K₄ is a fourth constant, G₁ is a first glucose concentration, K₅ is a fifth constant, T₁ is a first temperature threshold and K₆ is a sixth constant.

6. The method of claim 5, in which the correction value is about zero when the temperature value is about equal to room temperature value.

7. The method of claim 6, in which the room temperature is about 22 degrees Celsius.

8. The method of claim 5, said method further comprising the additional steps of:

determining whether the applied sample is a control solution; and

calculating the correction value with a third function if the applied sample is control solution.

12. A method for measuring a temperature corrected glucose concentration over a temperature range, the method comprising the steps of:

applying in a test meter a first test voltage for a first time between a first electrode and a second electrode in communication with a sample disposed on a test strip within the test meter, the first time interval being sufficient to oxidize a reduced mediator at the second electrode;

following the application of the first test voltage, applying a second test voltage for a second time interval between the first electrode and the second electrode sufficient to oxidize the reduced mediator at the first electrode;

calculating a first glucose concentration based on test current values during the first time interval and the second time interval;

measuring a temperature value using a temperature reading device incorporated into the test meter that receives the test strip; and

calculating a temperature corrected glucose concentration based on the first glucose concentration and the temperature value, wherein the step of calculating the temperature corrected concentration includes the additional steps of;

calculating a correction value based on the temperature value and the first glucose concentration;

calculating a temperature corrected concentration based on the first glucose concentration and the correction value, wherein the correction value is calculated with a first function if the temperature value is greater than a first temperature threshold, wherein the correction value is calculated with a second function if the temperature value is not greater than a first temperature threshold, said method further including the steps of

determining whether the applied sample is a control solution; and

calculating the correction value with a third function if the applied sample is a control solution, and in which the third function is a third equation, the third equation being;

Corr₂=−

K₇(T−

T_RT)+K₈×

G₁(T−

T_RT)

where Corr₂ is the correction value, K₇ is a first constant, T is a temperature value, T_RT is a room temperature value, K₈ is a second constant and G₁ is the first glucose concentration.