During the last year, in addition to the routine followed in the metabolic wards of the University Hospital in the care and treatment of patients with diabetes mellitus, we have attempted to determine the cause and conditions leading to the rapid loss or gain of weight in patients suffering from this disease. Any one working with diabetes has been surprised to note the gain in weight of certain types of patients while undergoing starvation. It is not a new condition, arising entirely from1Allen's treatment. In earlier days it was often found that patients gained weight on the "Oatmeal cures," or lost rapidly as coma approached. Rapid loss or gain in weight, the total calories remaining at the same level, occurs in normal individuals with alterations in amount of fat, carbohydrate and protein in their diets. Joslin2asserts that a high carbohydrate diet is apt to increase the weight and