Evaluation of hypothalamic-pituitary-adrenal axis in amenorrhoeic women with insulin-dependent diabetes

Diabetes is associated with a higher incidence of secondary hypogonadotrophic amenorrhoea. In amenorrhoeic women with insulin-dependent diabetes a derangement in hypothalamic-pituitary-ovary axis has been proposed. No data exist on hypothalamic-pituitary-adrenal function in these women. Gonadotrophin releasing hormone (GnRH), corticotrophin releasing hormone (CRH), metoclopramide and thyroid releasing hormone (TRH) tests were performed in 15 diabetic women, eight amenorrhoeic (AD) and seven eumenorrhoeic (ED). Frequent blood samples were taken during 24 h to evaluate cortisol plasma concentrations. There were no differences between the groups in body mass index, duration of diabetes, insulin dose and metabolic control. The AD women had lower plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, oestradiol, androstenedione and 17-hydroxyprogesterone (17-OHP) than the ED women. The responses of pituitary gonadotrophins to GnRH, and of thyroid stimulating hormone (TSH) to TRH, were similar in both groups. The AD women had a lower prolactin response to TRH and metoclopramide, and lower ACTH and cortisol responses to CRH, than the ED women. Mean cortisol concentrations > 24 h were higher in the amenorrhoeic group. Significant differences in cortisol concentrations from 2400 to 1000 h were found between the two groups. Insulin-dependent diabetes may involve mild chronic hypercortisolism which may affect metabolic control. Stress-induced activation of the hypothalamic-pituitary-adrenal axis would increase hypothalamic secretion of CRH. This would lead directly and perhaps also indirectly by increasing dopaminergic tonus to inhibition of GnRH secretion and hence hypogonadotrophic amenorrhoea. Amenorrhoea associated with metabolically controlled insulin-dependent diabetes is a form of functional hypothalamic amenorrhoea that requires pharmacological and psychological management.