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, HbA_1c, 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.