Background and aims:In a population-based cohort study with older subjects and without specific interventions, we investigated the impact of body mass index (BMI) and BMI change (as well as waist circumference and change of waist circumference) on reversion from prediabetes to normal glucose tolerance (NGT) and on long-term persistence of NGT.Materials and methods:Oral glucose tolerance tests were conducted at baseline and at follow-up in a cohort study in Southern Germany (KORA S4/F4; 1223 subjects without diabetes aged 55-74 years at baseline in 1999-2001; 887 subjects (73%), of whom 436 had prediabetes at baseline, participated in the follow-up 7 years later).Results:BMI reduction, but not initial BMI, predicted reversion from prediabetes to NGT. The odds ratio (OR) for returning to NGT was 1.43 (95% CI: 1.18-1.73) for a BMI decrease of 1 kg m(-2), after adjustment for age, sex, baseline glucose values and lifestyle factors. Initial BMI had no effect on reversion to NGT (OR=0.98, 95% CI: 0.91-1.06, per kg m(-2)). Persistence of NGT was associated with baseline BMI (OR=0.94, 95% CI: 0.88-0.998) and BMI reduction (OR=1.16, 95% CI: 1.02-1.33, per decrease by 1 kg m(-2)). For waist circumference and change of waist circumference similar results were obtained.Conclusion:In older adults, weight loss strongly increased the chances of returning from prediabetes to NGT irrespective of initial BMI. Long-term persistence of NGT depended both on initial BMI and on BMI change.