Glucose-induced insulin secretion in patients with parathyroid disorders.

Glucose-induced insulin secretion was studied in ten patients with primary hyperparathyroidism and two with idiopathic hypoparathyroidism both before and after treatment. In each individual, insulin secretion during an intravenous glucose tolerance test was greater when the plasma calcium was higher. No consistent change in insulin secretion with plasma calcium concentration was observed during an oral glucose tolerance test. These findings could be explained by the suggestion that insulin secretion provoked by orally administered glucose is enhanced by gut hormones which may stimulate insulin secretion by a mechanism independent of extracellular calcium.