FASTING PROINSULIN AND 2-H POSTLOAD GLUCOSE-LEVELS PREDICT THE CONVERSION TO NIDDM IN SUBJECTS WITH IMPAIRED GLUCOSE-TOLERANCE - THE HOORN STUDY

The aims of the present study were to observe the natural history of i mpaired glucose tolerance and to identify predictors for development o f non-insulin-dependent diabetes mellitus (NIDDM). A survey of glucose tolerance was conducted in subjects aged 50-74 years, randomly select ed from the registry of the middle-sized town of Hoorn in the Netherla nds. Based on the mean values of two oral glucose tolerance tests subj ects were classified in categories of glucose tolerance according to t he World Health Organization criteria. All subjects with impaired gluc ose tolerance (n = 224) were invited to participate in the present stu dy, in which 70% (n = 158) were subsequently enrolled. During follow-u p subjects underwent a repeated paired oral glucose tolerance test. Th e mean follow-up time was 24 months (range 12-36 months). The cumulati ve incidence of NIDDM was 28.5% (95% confidence interval 15-42%). Age, sex, and anthropometric and metabolic characteristics at baseline wer e analysed simultaneously as potential predictors of conversion to NID DM using multiple logistic regression. The initial 2-h post-load plasm a glucose levels and the fasting proinsulin levels were significantly (p < 0.05) related to the incidence of NIDDM. Anthropometric character istics, the 2-h post-load specific insulin levels and the fasting proi nsulin/fasting insulin ratio were not related to the incidence of NIDD M. These results suggest that beta-cell dysfunction rather than insuli n resistance plays the most important role in the future development o f diabetes in a high-risk Caucasian population.