Abstract
The effect of the dopamine agonist, bromocriptine, and the dopamine antagonist, metoclopramide, on glucose tolerance was examined in maturity onset diabetics and normal subjects. After bromocriptine there was a lowered fasting blood glucose and improved glucose tolerance in the diabetics. The controls showed an initial improvement in glucose tolerance. A reduction in insulin levels and a marked fall in plasma prolactin was observed in all subjects. Growth hormone concentrations were low and unaffected in the diabetics, and there was an inconsistent rise in the normals. After metoclopramide there was some impairment in glucose tolerance in the normal subjects, but this was not significant in the diabetics. There was also a marked prolactin release in all subjects, but no significant effect on insulin or growth hormone. It is concluded that bromocriptine lowers the blood glucose and improves glucose tolerance in maturity onset diabetics. This action may be the result of the lowered prolactin which occurred without a concomitant rise in growth hormone.