Hyperthyroidism and diabetes mellitus. An analysis of 70 patients.

Hyperthyroidism developed in 70 patients with diabetes mellitus. Nine patients had masked hyperthyroidism with weight loss as the main sign. Diabetic control deteriorated in 28 of 48 insulin-dependent patients and in four of 22 taking hypoglycemic agents orally. Recurrent ketoacidosis occurred in two. Insulin requirements increased in 11 of 48 by 25% to 100% (mean, 50%). Following treatment of the hyperthyroidism, insulin requirements decreased in 13 of 48 by 20% to 100% (mean, 35%). Four of 22 patients were changed from orally ingested hypoglycemic drugs to insulin. Because of similar symptoms, underlying hyperthyroidism must be considered in any patient whose diabetes is poorly controlled.