Background: Patients with hyperparathyroidism have alterations in carbohydrate metabolism characterized by insulin resistance, hyperinsulinemia, and glucose intolerance. The clinical significance of these findings in the management of patients with diabetes mellitus (DM) after parathyroidectomy for hyperparathyroidism has been controversial. Methods: A retrospective review identified 87 patients with DM and hyperparathyroidism who underwent parathyroidectomy. The follow-up documentation of 70 patients who underwent diabetic management was then evaluated to assess the benefit of parathyroidectomy on glucose management. Results: Thirteen patients had type 1 DM, and 74 patients had type 2 DM. Primary hyperparathyroidism was present in 93% of patients with type 2 DM; 64% of patients with type 1 DM had secondary hyperparathyroidism. At follow-up, glucose control was stable in 40% of patients, had improved in 37% of patients, and had deteriorated in 23% of patients (P = .003). Improved glucose control was not dependent on age, duration of DM, duration of hyperparathyroidism, length of follow-up, or calcium levels. The patients with decreased requirements had a significantly lower parathyroid hormone level (P = .05). Improved glucose control was most significant in patients whose condition was managed with oral hypoglycemics (P = .05) or insulin (P = .03). Conclusions: The clinical and laboratory investigations on the influence of hyperparathyroidism on DM support the benefit of parathyroidectomy in patients with DM. Patients with type 1 and type 2 DM show improvement in glucose control after parathyroidectomy. The presence of DM and hyperparathyroidism is an indication for parathyroidectomy because it results in either stabilization or improved glucose control in 77% of patients. (Surgery 1999:126:1160-6.)
