Methimazole treatment aggravates low-dose streptozotocin-induced diabetes

Treatment of mice with methimazole was found to modulate diabetes development following low-dose (5 x 40 mg/kg body weight) streptozotocin administration. The administration of 0.2 or 1 mg methimazole per kg body weight for 1-3 weeks significantly enhanced hyperglycemia. The enhancing effect of methimazole was also seen when administration began only after termination of streptozotocin injections. Methimazole treatment did not potentiate diabetes induced by a single high dose of streptozotocin (175 mg/kg). Serum thyroxin levels were not affected due to the short period of thyrostatic treatment. Semiquantitative immunocytochemistry of inflamed islets did not show a stronger influx of immune cells but rather a high activation state of infiltrated macrophages (M1/70 positive). We conclude that methimazole enhances the development of immune-mediated diabetes.