Clinical Evaluation of Measuring Glycosylated Hemoglobin Levels for Assessing the Long-term Blood Glucose Control in Diabetics

Abstract

The glycosylated hemoglobin levels were determined in the hemolysates obtained from 14 normal subjects and 67 patients with adult-onset diabetes mellitus, using the column chromatographic procedure of Trivelli et al. The levels of hemoglobin A_1a+b (HbA_1a+b) and HbA_1c and the sum of HbA_1a+b and HbA_1c (HbA_1a+b+HbA_1c) in normal subjects averaged 2.3±0.4 (SD)%, 5.3±0.8% and 7.6±1.0%, respectively. Although a slight increase in HbA_1a+b was found in patients with diabetes mellitus (mean±SD=2.8±0.7%), it was not significantly different from that in normal subjects. Despite the wide range, HbA_1c and HbA_1a+b+HbA_1c were significantly increased in patients with diabetes mellitus (6.9±1.8% for HbA_1c, p<0.01 and 9.7±2.2% for HbA_1a+b+HbA_1c, p<0.01). A significant correlation existed between the glycosylated hemoglobins and plasma glucose levels determined in the same blood (r=+0.57, p<0.001). Moreover, the glycosylated hemoglobin levels correlated significantly with the average glucose levels for several months preceding the hemoglobin measurements. In particular, a striking correlation was evident in the plots of HbA_1a+b+HbA_1c against the mean plasma glucose for 3 months prior to the hemoglobin measurements, which had a correlation coefficient of 0.79 (p<0.001). The present findings revealed that the glycosylated hemoglobins reflect the time-averaged blood glucose levels in diabetics for during approximately the proceding 3 months, indicating the usefulness of measuring the glycosylated hemoglobins in assessing the long-term blood glucose control in diabetics.