What causes impaired glucose tolerance to deteriorate or normalize?

Twenty-five middle-aged subjects with impaired glucose tolerance (IGT) were analysed 5 years later, showing normal glucose tolerance in 28% and persistent glucose deterioration in 72%. Body mass index (strongly) and 2-h glucose levels were clinically useful predictors, in the newly detected IGT-subjects, of persistent glucose deterioration (IGT or NIDDM) 5 years later. The frequency of hypertension was 36% in the newly-detected IGT subjects. Five years later this frequency increased to 54% in the persistently hyperglycaemic group, and decreased to none in the normalized group. Predictors of hypertension at the follow-up were baseline blood pressure and parts of the hyperinsulinaemic syndrome, such as serum triglyceride at baseline, BMI and 2-h glucose at the follow-up. Microalbuminuria (greater than 20 mg day-1) was not found at the 5-years follow-up, either if the subjects then had NIDDM, IGT or normal glucose tolerance. ECG abnormalities (ST segment and T wave changes) were two-fold more prevalent in the group with IGT or NIDDM than in the normalized group at the follow-up. Predictors were baseline BMI and incremental BMI. In conclusion, obesity and high 2-h glucose in newly-detected IGT-subjects seemed to predict the persistence of IGT 5 years later. Hypertension, but not microalbuminuria, was frequent when glucose deterioration persisted.