Method for determining glucose concentration in tissue fluid
The invention relates to a method and a device for determining the glucose concentration in tissue fluid whereby test values for glucose and for an endogenous reference substance are detected in a sample liquid obtained by microdialysis, microperfusion or ultrafiltration, and the glucose value is corrected in accordance with the test value for the reference substance. The recovery rate for glucose is determined from a non-linear relationship with the recovery rate for the ionic reference substance, and the test value for glucose is corrected therewith. In addition, the concentration of lactate and/or pyruvate is used as a further reference substance in the sample liquid to make further corrections.
1. A method for determining glucose concentration in a tissue fluid in a body, the method comprising the steps of:
measuring a glucose concentration in a sample of the tissue fluid obtained by a technique selected from the group consisting of microdialysis, microperfusion, and ultrafiltration;
measuring a concentration of at least one reference substance in the sample of the tissue fluid; the at least one reference substance including lactate and pyruvate;
determining the glucose concentration of the tissue fluid in the body based upon the measured concentration of the at least one reference substance and glucose in the sample of the tissue fluid.
2. The method as set forth in claim 1 further including the step of determining a concentration ratio of lactate to pyruvate in the sample of the tissue fluid in order to determine the glucose concentration in the tissue fluid in the body.
3. The method as set forth in claim 2 further including the step of utilizing a linear correction factor to determine the glucose concentration in the tissue fluid in the body when the concentration ratio of lactate to pyruvate in the sample of the tissue fluid is within the range between about 10:1 to about 20:1.
4. The method as set forth in claim 2 further including the step of utilizing a constant to determine the glucose concentration in the tissue fluid in the body when the concentration ratio of lactate to pyruvate in the sample of the tissue fluid is about 20:1.