Implications of point-of-care testing for hemoglobin A1c.

Abstract

527 ANOVEL POINT-OF-CARE device for determining hemoglobin A1c (Hb A1c) is described in this issue of Diabetes Technology and Therapeutics.1 Point-of-care testing (POCT) at physicians’ offices for Hb A1c will reduce the cost of testing, eliminate the time delay between sample collection and availability of the test result, and enhance diabetes care. Along with the expected benefits of POCT for Hb A1c, other questions need to be considered. For example, is National Glycohemoglobin Standardization Program (NGSP) certification needed for point-of-care devices? What is the optimum frequency of Hb A1c measurement? Should these devices be approved for at-home use by patients? Lastly, is Hb A1c appropriate for use as a screening tool for diabetes? The NGSP standardizes Hb A1c test results to Diabetes Control and Complications Trial (DCCT) equivalent values. The American Diabetes Association (ADA) states that it is desirable that laboratories use only assay methods that have passed NGSP certification testing,2 and at least one manufacturer of a point-of-care device for Hb A1c testing is NGSP-certified.3 Test results from the NGSP-certified devices are desirable because results provided to health-care providers and patients are traceable to the DCCT results associated with mean blood glucose and the risk of diabetic complications.3 The ADA recommends an initial Hb A1c determination followed by quarterly measurements.4 For persons who meet their therapeutic goals with stable glycemic control, the frequency of monitoring is less.4 For persons who require therapeutic regimen adjustments or encounter difficulty meeting therapeutic goals, the frequency of monitoring is more.4 Conventionally controlled and intensively controlled DCCT participants were monitored quarterly and monthly, respectively5; thus frequent POCT for Hb A1c may be required to achieve intense glycemic control and should facilitate a close relationship between the health-care team and the patient. An obvious option is to offer these devices to patients for over-the-counter or prescribed at-home use. However, at-home determination of Hb A1c may not enhance diabetes care. Interpretation of Hb A1c test results require knowledge of the association between blood glucose and Hb A1c, the kinetics of Hb A1c, and the limitations of the selected assay.2 Patients are unlikely to possess the training and knowledge to appropriately interpret such results. Even if patients interpreted the results correctly, how would they use the information received