[Insulin resistance in pituitary, thyroid, and adrenal diseases]

Patients with acromegaly, Cushing's syndrome, and Graves' disease often have impaired glucose tolerance with high insulin secretion. Persistent elevation of serum GH levels has insulin-antagonistic effects on peripheral tissues. The number of insulin receptors on monocytes is decreased in patients with acromegaly. The expression of GLUT-1 glucose transporters is also decreased in GH-treated adipocytes in vitro. Insulin resistance in patients with Graves' disease may be due to antagonism between the effect of insulin and hyperthyroidism at the hepatic level. Glucocorticoids also have insulin-antagonistic effects on both hepatic and extrahepatic tissues, although the precise mechanism still remains to be elucidated. Insulin resistance in these patients can be improved after successful treatment of their endocrine diseases.