Comparison of glycosylated hemoglobin with the oral glucose tolerance test. A study in subjects with normoglycemia, glucose intolerance and non-insulin-dependent diabetes mellitus.

At a health survey of 819 subjects, 47-54 years old, the rate of glucose intolerance (GI) was 6.2% (51 subjects) according to 75 g oral glucose tolerance tests (OGTT) and WHO criteria. In GI-subjects, the mean HbA1 was 7.3% (10th-90th percentile range 6.2-8.3%), and significantly higher than the mean HbA1 in 150 subjects with normal OGTT, which was 6.5% (10th-90th percentile range 5.7-7.4%). With an upper normal limit of 7.8% (mean + 2 SD) only 20% of all GI-subjects had a raised HbA1. The differences between 31 GI-subjects, with low HbA1 (mean 6.9%), and 20 GI-subjects, with relatively high HbA1 (mean 7.9%), were not significant with respect to fasting and 2-hour blood glucose, area under glucose curve, body mass index, index of physical activity, rate of hypertension or rate of first degree relatives with diabetes. In an unselected group of 157 subjects, sampled consecutively during the first part of the survey, the mean HbA1 was 6.6% (10th-90th percentile range 5.8-7.5 %) 150 subjects were those with normal OGTT, 6 subjects had GI and only one subject had previously unknown diabetes. No distinct correlations between HbA1 and OGTT fasting or 2 hour values were found in this sample. No correlation was found within the separate groups of 51 GI-subjects and 150 normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)