[Improvement of diabetes mellitus after excision of a parathyroid adenoma]

Disturbances of glucose metabolism with hyperinsulinism and peripheral insulin resistance are frequently observed in patients with hyperparathyroidism. The mechanism of how hyperparathyroidism affects glucose metabolism is not known. Hypercalcemia, hypophosphatemia and the parathyroid hormone itself seem to be involved. However, parathyroidectomy exerted rather variable effects on glucose metabolism: In patients with fully developed diabetes mellitus both, a complete normalisation of glucose tolerance as well as no change 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 elevated. After successful operation of a parathyroid adenoma there was a marked improvement in diabetes, and the patient's insulin requirement decreased to one third of the preoperative dose. This case further illustrates the association between primary hyperparathyroidism and diabetes mellitus and the potential improvement of the metabolic situation after parathyroidectomy.