RESEARCH DESIGN AND METHODS - The study consisted of a 1 2-month randomized controlled trial of 147 health plan members with type 2 diabetes and obesity (BMI > or =27 kg/m^sup 2^). Participants were randomized to lifestyle case management or usual care. Case management entailed individual and group education, support, and referral by registered dietitians; intervention cost was $350 per person. Individuals treated with usual care received educational material. Both groups received ongoing primary care. Outcomes were difference between groups for change in weight (kilograms), waist circumference (centimeters), HbA^sub 1c^, fasting lipid levels, use of prescription medications, and health-related quality of life.