Oral glucose tolerance test--can the reflectance meter replace laboratory-based methods?

Sixteen national servicemen detected to have glycosuria on routine medical examination were subjected to 3 successive oral glucose tolerance tests. Capillary blood glucose was measured by reflectance meter in the first test (oGTT1), venous whole blood glucose by Beckman Synchron CX3 Analyser in the second (oGTT2) and by both methods in the third (oGTT3). In oGTT1, 1 subject was classified as diabetic and 15 as Impaired Glucose Tolerance (IGT). In oGTT3, using capillary blood glucose, 1 was diabetic, 8 IGT and 7 normal. Using venous whole blood, in oGTT2, 1 was diabetic, 3 IGT and 12 normal as compared to 1 diabetic, 4 IGT and 11 normal in oGTT3. There is considerable variation in classification as a result of using capillary blood glucose measured by reflectance meter as compared to the laboratory-based method. Capillary blood glucose measurement for oral glucose tolerance test cannot be recommended.