The prevalence of diabetes mellitus (DM) and the metabolic syndrome (MetS) are rapidly increasing in Asia including Korea. In 2005, the Third Korea National Health and Nutrition examination survey (KNHANES III) reported that the prevalence of DM and MetS in adults was estimated to be 8.7% and 32.6%, respectively. In our study of 688 type 2 DM patients, MetS prevalence was 46.9% for males, and 65.1% for females. Patients with T2DM and MetS showed significantly higher insulin resistance than T2DM without MetS, confirming that insulin resistance is an important feature of MetS in T2DM patients. Patients with T2DM and MetS showed higher BMI, waist circumference, blood triglycerides, atherogenic index, C-reactive protein and lower HDL-cholesterol. In recent years, concerns with regard to the association of diet with MetS have grown. In our study with non-DM elderly people, higher % energy from carbohydrate, and lower intakes of antioxidant vitamins were considered to be associated with the risk of MetS. Patients with T2DM and MetS showed significant positive correlations between intakes of energy, carbohydrate, protein and lipids with BMI, weight, as well as waist circumference. These associations were not found in patients with T2DM without MetS. Nutritional risk factors for MetS among middle-aged T2DM subjects would be excessive carbohydrate intake with low intakes of fat, protein, vitamins, and minerals.