Aims/hypothesis: We sought to identify determinants of progression from impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) to diabetes in high-risk screened individuals.
Methods: In general practices in Denmark, stepwise screening for type 2 diabetes mellitus in persons aged 40 to 69 years included a risk questionnaire, random blood glucose, HbA1c, fasting blood glucose and an OGTT. The 1,821 individuals with IGT or isolated IFG (WHO 1999) were re-invited after 1 and 3 years. Follow-up data on glucose measurements were available in 1,510 individuals and additional clinical data in 1,002 collected at the 3-year visits. Regression models using interval censoring were used.
Results: Progression rates from IFG and IGT to diabetes over 3.5 years were 11.8 and 17.0 per 100 person-years, respectively and were particularly high in the first year. Baseline determinants of progression were: IFG: glucose measures, BMI [per kg/m2, rate ratio (RR) 1.04 (95% CI, 1.01-1.08)] and triacylglycerol [per twofold increase, RR 2.19 (1.49-3.22)]; and IGT: glucose measures and known hypertension [RR 1.46 (1.11-1.93)]. Weight reduction and decreased triacylglycerol were inversely associated with development of diabetes in IFG individuals [per 1 kg/year, RR 0.81 (0.66-0.98) and per 1 mmol l(-1) year(-1), RR 0.08 (0.01-0.51), respectively], whereas in IGT participants only weight reduction was inversely associated [per 1 kg/year, RR 0.80 (0.67-0.96)].
Conclusions/interpretation: Higher levels of glucose measures, larger BMI, known hypertension and hypertriacylglycerolaemia are significant determinants of progression in high-risk screened individuals. Weight loss of 1 kg/year or reduction of hypertriacylglycerolaemia markedly reduced the risk of diabetes.