The relationship between primary hyperparathyroidism and diabetes mellitus.

Previous reports have suggested that control of diabetes improves after successful parathyroidectomy for primary hyperparathyroidism. To investigate this proposition further, a review was made of all insulin-requiring diabetics undergoing curative parathyroidectomy at the Mayo Clinic between 1970 and 1984 (36 patients). All contemporary insulin-requiring diabetics undergoing thyroidectomy for benign euthyroid disease served as a control group (34 patients). One patient in each group had type I diabetes mellitus, and the remainder had type II diabetes mellitus. Preoperative insulin requirements, insulin requirements at follow-up, and change in insulin requirements did not differ significantly between the two groups. This study suggests that parathyroidectomy does not lead to a statistically significant reduction in the insulin requirements of diabetic patients with primary hyperparathyroidism and that coexistent type II diabetes mellitus should not be considered a further indication for parathyroidectomy in patients with primary hyperparathyroidism.