The Effect of Blood Glucose Concentration on Labile A_1c in Diabetic Patients

We investigated the magnitude of labile A_1c in total A_1c measured rapidly by a chromatographic method, and whether or not there was an effect of blood glucose before and after a meal on labile A_1c in 94 type I and 178 type II diabetic subjects. There were strong correlations between serum glucose and labile A_1c both in type I (r = 0.76, P < 0.001) and in type II diabetic subjects (r = 0.72, P < 0.001). These relationships did not change before and after the meal. As labile A_1c increased in proportion to blood glucose, it could be calculated from the blood glucose level in simultaneous blood samples. In type I diabetic subjects, below the 100-mg/dl glucose level labile A_1c was negligible, and above 100 mg/dl about 0.35% labile A_1c was increased every 50-mg/dl increment of glucose. In type II diabetic subjects, below a 150-mg/dl glucose level labile A_1c was in the normal range (0.58 ± 0.15%), and above the 150-mg/dl glucose level every 50-mg/dl increment of glucose increased about 0.3% of labile A_1c. If this process is used, stable A_1c can be calculated easily from total A_1c and coincident serum glucose, even though labile A_1c is not removed by incubation.