OBJECTIVE: To evaluate the clinical effects of a comprehensive prepackaged meal plan, incorporating the overall dietary guidelines of the American Diabetes Association and other national health organizations, relative to those of a self-selected diet based on exchange lists in free-living individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 202 women and men (BMI < or = 42 kg/m2) whose diabetes was treated with diet alone or an oral hypoglycemic agent were enrolled at 10 medical centers. After a 4-week baseline period, participants were randomized to a nutrient-fortified prepared meal plan or a self-selected exchange-list diet for 10 weeks. On a caloric basis, both interventions were designed to provide 55-60% carbohydrate, 20-30% fat, and 15-20% protein. At intervals, 3-day food records were completed, and body weight, glycemic control, plasma lipids, and blood pressure were assessed. RESULTS: Food records showed that multiple nutritional improvements were achieved with both diet plans. There were significant overall reductions in body weight and BMI, fasting plasma glucose and serum insulin, fructosamine, HbA1c, total and LDL cholesterol, and blood pressure (P < 0.001 or better for all). In general, differences in major end points between the diet plans were not statistically significant. CONCLUSIONS: Glycemic control and cardiovascular risk factors improve in individuals with type 2 diabetes who consume diets in accordance with the American Diabetes Association guidelines. The prepared meal program was as clinically effective as the exchange-list diet. The prepared meal plan has the additional advantages of being easily prescribed and eliminating the complexities of meeting the multiple dietary recommendations for type 2 diabetes management.