According to results from a landmark clinical study, as many as 10 million Americans who are at high risk for type 2 diabetes can sharply lower their chance of getting the disease through diet and exercise.

In the trial involving 3,234 people who already showed signs of impaired glucose tolerance, those who lost 5-7% of their body weight and walked or performed other moderate physical activity for 30 minutes a day reduced their risk of getting type 2 diabetes by 58%. Those taking metformin reduced their risk by 31%. In the group of patients receiving standard treatment, 29% developed diabetes; 14% of those in the diet-and-exercise group and 22% of those in the metformin group developed diabetes during the three-year follow-up period.

The findings were hailed as the first major trial to show that diet and exercise can effectively delay diabetes in a diverse American population of overweight people with impaired glucose tolerance. The results were so striking that the trial, which was sponsored by NIH, ADA and others, was halted a year earlier than planned. Because the follow-up period was only three years, the investigators cannot say that diabetes has been prevented, only delayed.

Related information: Risks | Lifestyle: diet, exercise