An important factor in medical nutritional therapy for elderly patients with diabetes is optimization of energy intake and macronutrient composition, with consideration of the food source and quality of nutrient. In addition, malnutrition and vitamin deficiency should be carefully considered. A dietary pattern that includes a high intake of vegetables, legumes, seaweed, and fish and a low intake of refined grains, sweets, sugar-sweetened beverages, and alcohol is favorable for diabetic patients. Particular attention should be paid to the excessive intake of sweets and fruits. Furthermore, the type and degree of physical function, cognitive function, lifestyle, social factors, medication, and hospitalization vary among elderly individuals. Therefore, individualized medical nutritional therapy that takes into account all these factors is essential.