Efficacy of diet and exercise in reducing body weight and conversion to overt diabetes.

The study by Wing et al. (1) evaluates the efficacy of diet and exercise, separate or combined, in reducing body weight and conversion to overt diabetes. The conversion to diabetes did not significantly differ among the treatment groups. Study participants whose baseline glucose tolerance tests demonstrated impaired glucose tolerance (1GT) were more likely to develop diabetes. Only 6% of those with normal glucose tolerance developed diabetes, compared with 25% of those with IGT. A weight loss of 4.5 kg reduced the risk of developing diabetes in those with normal glucose tolerance at study entry, as well as those with IGT. The study was conducted using the 1979 criteria for diabetes and IGT (2), but the results were similar when the 1997 criteria for diabetes (3) were used to estimate conversion.