Hyperinsulinaemia in hyperprolactinaemic women.

The metabolic sequelae of hyperprolactinaemia were studied over a 12 h period of normal meals and activity in nine young females hyperprolactinaemic subjects and fourteen matched controls. In the patients, fasting blood glucose and serum insulin concentrations were normal, as was the blood glucose response to meals; the insulin rise with meals was, however, exaggerated and hyperinsulinaemia persisted throughout the day (mean +/- SEM 12 h serum insulin, 26 +/- 8 vs. 16 +/- 9 mu/l, P < 0.01). Blood lactate, pyruvate and alanine response to meals was also increased. Blood glycerol (mean 12 h blood glycerol 0.06 +/- 0.01 vs. 0.09 +/- 0.01 mmol/l, P < 0.01) and blood 3-hydroxybutyrate (mean 12 h blood 3-hydroxybutyrate 0.03 +/- 0.01 vs. 0.05 +/- 0.01 mmol/l, P < 0.05) concentrations were lower in hyperprolactinaemic subjects. There was a strong negative correlation between mean insulin and mean 3-hydroxybutyrate levels in the afternoon period (rs = -0.92, P < 0.01). Excess circulating prolactin in young female is associated with normoglycaemic hyperinsulinaemia. The changes in blood metabolite levels observed are probably secondary to the increased insulin concentrations.