Differences in pituitary and testicular function between diabetic patients on insulin and oral anti-diabetic agents.

Abstract

Pituitary responsiveness to thyrotrophin releasing hormone (TRH) and luteinizing hormone releasing hormone (LHRH) was studied in thirty one male diabetics, of whom sixteen were insulin-dependent and fifteen on oral antidiabetic agents. Ten age-matched controls were also studied. TRH and LHRH were simultaneously administered intravenously, each in a small dose of 10 μg followed two hours later by 190 μg and 90 μg respectively. Basal hormone levels were measured in a further group of thirty six patients (twelve on insulin, twelve on oral agents and twelve on dietary restrictions alone). Higher thyrotrophin (TSH) response was observed following the small dose of TRH in the patients treated with oral agents than in the control subjects. The response of prolactin was lower in patients treated with oral agents compared with those treated with insulin. There was no difference in plasma T3 and T4 levels in the patients treated with insulin or oral agents. Significantly higher basal growth hormone (GH) levels were observed in the diabetics. The insulin-dependent group showed a more marked response of GH to TRH/LHRH. No response was observed in the controls. Plasma testosterone levels were significantly lower in the oral agent group (13.8 nmol/l) than in the insulin group (19.4 nmol/l), patients on dietary restrictions (18.4 nmol/l) and the control subjects (19.0 nmol/l). The LH response to the smaller dose of LHRH was impaired in patients on insulin and oral agents. There was a significant difference in FSH response between impotent and sexually normal patients.