CHLOROTHIAZIDE is widely used in the treatment of pregnant patients with edema.1 When this condition is complicated by diabetes, the increased excretion of sodium, potassium, and chlorides due to this drug may accelerate ketosis. Two cases of diabetes with pregnancy in whom acidosis may have been aggravated by administration of chlorothiazide are here described. Case Reports Case 1.— A 38-year-old housewife was admitted to Providence Hospital, Washington, D. C., on Oct. 30, 1959, complaining of low abdominal pains. She had been a diabetic for 21 years and at the time of admission was 7 months pregnant. Expected confinement date was Dec. 22, 1959. At 3 months gestation her diabetes was well controlled by 10 units of isophane (NPH) insulin a day. She then noted persistent glycosuria and gradually increased the insulin dose to 40 units of isophane at 6 A. M., supplemented by 10 to 20 units of regular