Improvement of diabetes mellitus after operation of a parathyroid adenoma

Disturbances of glucose metabolism with hyperinsulinism and peripheral insu lin resistance are frequently observed in patients with hyperparathyroidism . The mechanism of how hyperparathyroidism affects glucose metabolism is no t known. Hypercalcemia, hypophosphatemia and the parathyroid hormone itself seem to be involved. However, parathyroidectomy ex erted rather variable e ffects on glucose metabolism: In patients with fully developed diabetes mel litus both, a complete normalisation of glucose tolerance as well as no cha nge in the metabolic situation have been observed. We report a 64-year old female patient with primary hyperparathyroidism and diabetes mellitus. The patient had severe insulin resistance with insulin requirements of 200 IU/day. Fasting insulin and C-peptide levels were eleva ted. After successful operation of a parathyroid adenoma there was a marked improvement in diabetes, and the patient's insulin requirement decreased t o one third of the preoperative dose. This case further illustrates the ass ociation between primary hyperparathyroidism and diabetes mellitus and the potential improvement of the metabolic situation after parathyroidectomy.