OBJECTIVE: To examine the impact of a 12-week walking program on body composition and risk factors for cardiovascular disease in women with type 2 diabetes and in normoglycemic women with first-degree diabetic relatives. RESEARCH DESIGN AND METHODS: There were 11 postmenopausal women with type 2 diabetes and 20 normoglycemic women of similar age and BMI who were asked to walk 1 h per day on 5 days each week for 12 weeks. Fitness (estimated VO2max) was assessed with a 1.6-km walking test; body composition was measured by dual-energy X-ray absorptiometry; and sex hormone, metabolic, and lipid concentrations were measured in serum. RESULTS: After 12 weeks, estimated VO2max improved in both groups (P < 0.005). In the diabetic women, BMI and fat content of the upper body and android waist region decreased (P < 0.05). Concentrations of fasting blood glucose (P < 0.05) HbAlc (P < 0.05), total cholesterol (P < 0.005), and LDL cholesterol (P < 0.05) decreased, while HDL cholesterol and sex hormones were unchanged. In contrast, normoglycemic women failed to lose body fat after 12 weeks of exercise in a walking program. However, their HbAlc, total cholesterol, LDL cholesterol, sex hormone-binding globulin, and total testosterone concentrations decreased (P < 0.05). On pooling the data and including diabetes as a categorical grouping variable, stepwise multiple regression analysis indicated that the change in centralized body fat, but not the change in VO2max, was related to change in fasting blood glucose. CONCLUSIONS: Twelve weeks of walking increased the fitness of diabetic and normoglycemic women. Improvement of fasting blood glucose was related to the loss of centralized body fat rather than to improved fitness.