GLYCATED HEMOGLOBIN PREDICTS PROGRESSION TO DIABETES-MELLITUS IN PIMA-INDIANS WITH IMPAIRED GLUCOSE-TOLERANCE

Glycated haemoglobin could offer several practical advantages over the OGTT for assessing glucose metabolism. Initial cross-sectional studies (1983-1985) on 381 subjects (mostly Pima Indians) described the relationship between HbA(1c) (a specific glycated Hb) and the OGTT. We performed follow-up OGTTs and HbA(1c) measurements on 257 of these same subjects 1.6-6.1 years later. Subjects were again grouped according to both the result of the OGTT (normal,IGT or diabetes, by WHO criteria) and HbA(1c) result: (normal or elevated based on mean +/- 1.96 SD of normal). Of 66 subjects with IGT at baseline, 47 (71 %) had normal HbA(1c) and 19 (29 %) had elevated HbA(1c). Twenty-six (39 %) of these subjects had diabetes at follow-up. Of these subjects with IGT, a significantly greater percentage of subjects with elevated HbA(1c) at baseline (68 %) showed worsening to diabetes than those with a normal-HbA(1c) (28%); (chi-square=7.8, df=1, p < 0.01). Thus, in subjects with IGT, glycated Hb may be a useful predictor of progression to diabetes.