Most recently, the U.S. Diabetes Prevention Program (9) demonstrated the efficacy of lifestyle intervention to prevent type 2 diabetes. This program, which is the largest trial of primary prevention of diabetes to date, was conducted at 27 clinical centers. More than 3000 overweight and obese participants with impaired glucose tolerance were randomly allocated to 1 of 3 study conditions: control, use of metformin, or intensive lifestyle intervention. The goal of lifestyle intervention was to achieve and maintain 7% or greater weight loss through a low-calorie, low-fat diet and 150 or more minutes of moderate physical activity weekly (9). Nearly half the participants were African American, Hispanic American, Asian American, or Native American. Over 3 years, weight loss in the placebo, metformin, and lifestyle intervention groups averaged 0.1 kg, 2.1 kg, and 5.6 kg, respectively. The incidence of diabetes was reduced by 31% in the metformin group and 58% in the lifestyle group; the latter value is identical to that observed in the Finnish study. To prevent 1 case of diabetes, only 7 patients needed to be “treated” with lifestyle change, compared with 14 patients treated with metformin. The magnitude of risk reduction in the lifestyle intervention group was similar across all ethnic groups, and participants in all age and body mass index subgroups achieved a clinically significant reduction in risk. In contrast, metformin was relatively ineffective in older and less obese participants.