Type 2 diabetes is a complex, multi-factorial condition, caused by environment factors and an inheritance pattern that is polygenic. Preventing diabetes is a major clinical, research and public health priority. Lifestyle intervention studies, programs that promote changes in diet, activity, and behavior, have been shown to be effective ways to prevent type 2 diabetes, perhaps even in patients with genotypes that might put them at increased risk for developing the disease. Clinicians should be helping their patients to make positive lifestyle changes, and researchers must find ways to translate lifestyle interventions into real world settings in order to stop the epidemic of diabetes.