Assessment of a Reference Procedure to Collect and Analyze Glucose in Capillary Whole Blood

Self-monitoring of blood glucose is used to assist patients with diabetes in achieving and maintaining blood glucose concentrations close to those found in individuals without diabetes. This goal requires that blood glucose monitors meet analytical performance criteria that are appropriate for patient care (1)(2)(3). The lack of accuracy of monitors and the resulting variability among monitors limit their use for assessing and maintaining glycemic control (4)(5).No suitable means exists for establishing calibration traceability between a glucose monitor and a reference method. In the absence of a whole-blood glucose reference material, the recommended approach to establishing traceability is to perform split-sample comparisons with patient samples and a reference method (6). This can be achieved by following the Clinical and Laboratory Standards Institute (NCCLS) EP9-A2 (7) guideline procedure. Because the capillary whole blood required by these monitors usually is available only in small amounts and because glucose is not stable in this matrix, such split-sample comparison studies are difficult to perform, particularly when specimens need to be transported elsewhere (8). Capillary collection devices have been used in method-comparison studies to characterize glucose monitors (8)(9)(10)(11)(12)(13), but data on the stability and reproducibility of glucose measurements of blood in these capillary collection devices are limited (8)(9). In this study, we assessed a capillary collection procedure in combination with a gas chromatography–mass spectrometry (GC/MS) reference method for measuring glucose in whole blood.The specimen collection procedure and measurement of glucose by GC/MS were based on a previously published method (9). The specimen collection procedure consisted of filling a 1-μL heparinized glass capillary with specimen and transferring it into a microcentrifuge tube …