Lack of effect of hyperprolactinemia on glucose disposal and insulin secretion in patients with prolactinomas.

The role of prolactin as a diabetogenic hormone is still controversial. The present study examines intravenous glucose tolerance in six subjects with prolactin secretion pituitary adenomas. Testing was performed in each individual both in the untreated high prolactin state and again after prolactin was reduced by bromocriptine treatment for three months. Lowering serum prolactin failed to improve intravenous glucose tolerance or alter insulin release. It is concluded that prolactin has no significant effect on glucose disposal.