Diet and exercise are basic measures of treatment of diabetes mellitus. To prevent the development and progression of atherosclerotic disease as well as microangiopathy, diet management should be focused on the reductions of conventional risk factors for atherosclerosis such as hyperglycemia, dyslipidemia, and hypertension. To control the these risk factors, both total energy and fat intake should be reduced. A diet high in mono- and poly-unsaturated fatty acids, and dietary fibers are recommended to diabetic patients, but the ideal ratio of saturated, monounsaturated, and polyunsaturated fatty acids should be determined from clinical and epidemiological studies in the future. A high concentration of plasma homocysteine is a new risk factor for atherosclerotic disease in diabetic patients. To reduce plasma homocysteine, diet enriched in folate and vitamin B12 may be recommended. A high intake of flavonoid, one of antioxidants, may be also recommended in diabetic patients because of its counteraction against increased oxidative stress in diabetes mellitus. Exercise therapy is an effective measure for improving glycemic control in Type 2 diabetic patients. However, the most appropriate kinds and strength of exercise in diabetic patients with complications or elderly diabetic patients still remain unknown. The dietary regimen or exercise of diabetic patients should be determined individually according to the risk factors, complications, and psychological and socioeconomic conditions.