As a part of a QOL study in elderly diabetes mellitus, we performed an interview conducted by professional interviewers on the sense of burden of dietary therapy in 383 elderly outpatients with diabetes mellitus aged over 60 years old. We used a scale on Burden of Dietary Therapy (BDT) that consisted of 7 questions (calorie restriction, dietary balance, regular dietary habits, restriction of favorite food, restriction of amounts of snacks, restrictions when eating out, burden of total dietary therapy). The sense of burden was rated from 1 (never burdened) to 4 (heavily burdened) for each question and the alpha coefficiency of the BDT scale was 0.80. Women, relatively younger elderly patients, hyperglycemic patients, or tablet-treated patients had higher BDT scale scores. The lower the positive family support scores and the higher the negative social support scores the greater was the BDT score. High BDT scores were significantly associated with low PGC moral scales (p < 0.001). The results suggest that the burden of dietary therapy could lower the quality of life in elderly patients with diabetes mellitus.