To decrease body weight and insulin resistance, a calorie-restricted diet-with minimal caloric intake required for daily activities-is the primary treatment strategy for patients with type 2 diabetes (T2D) in Japan. However, many patients cannot continue with this diet for long, because calorie restriction is difficult and nutritional balance is hard to understand. Carbohydrate-restricted diets are easier for patients than conventional calorie-restricted diet. In this study we aimed to elucidate the effects of a moderate carbohydrate-restricted diet on glucose metabolism and renal function in patients with T2D on dipeptidyl peptidase-4 (DPP-4) inhibitors. Nineteen outpatients with T2D continued on a moderate carbohydrate-restricted diet (targeting 50% of calories) for 6 mo. Meanwhile, 10 other outpatients with T2D on DPP-4 inhibitors had the conventional calorie-restricted diet using the food exchange table. No change in prescription drugs occurred for both groups during the study period. After the intervention, the carbohydrate content in dietary intake was lowered significantly from 56.8±8.3 to 46.8±10.1%, while the lipid concentration, primarily n-6 polyunsaturated fatty acids, was significantly increased. There was no significant change in protein intake. Hemoglobin A1c (HbA1c) fell from 7.22±0.74% to 6.95±0.72% (mean±SD). Furthermore, salt intake decreased significantly from 6.8±2.5 g prior to the intervention, to 5.7±1.9 g after the intervention. The estimated glomerular filtration rates (eGFR) decreased slightly, while serum creatinine levels did not change. These findings suggest that a moderate carbohydrate-restricted diet (50%) is effective in patients with T2D, without affecting kidney function.