Type 2 diabetes mellitus is a serious, growing, and costly public health problem. The disease is chronic and degenerative, and thus primary prevention is desirable. Observational studies have linked type 2 diabetes to specific lifestyle behaviors. Several recent major clinical trials confirm that type 2 diabetes can be delayed or prevented in people at high risk; multicomponent lifestyle modification can reduce the incidence of diabetes up to 58%. The American Diabetes Association has recently recommended that lifestyle interventions to prevent or delay diabetes be delivered to people with prediabetes. Delivery of lifestyle interventions in practice is fraught with challenges, but there are several tools and practical strategies available for the implementation of trial findings.