INSULIN-DEPENDENT DIABETES-MELLITUS AND MENSTRUAL DYSFUNCTION

Disordered reproductive function has long been recognized as a prevale nt problem among women of reproductive age who suffer from insulin-dep endent diabetes mellitus (IDDM). Delay in menarchial age is frequently seen if IDDM develops in the peripubertal years and some form of mens trual dysfunction is found in nearly one-third of all women of reprodu ctive age with IDDM. This review summarizes some of the prevailing vie ws regarding the mechanisms through which uncontrolled IDDM is thought to disrupt normal hypothalamic-pituitary-gonadal function. Although a nimal studies have suggested that poorly controlled IDDM may adversely affect the uterovaginal outflow tract and/or ovarian function, no cli nical studies have suggested that abnormal uterine or ovarian function underlies the menstrual dysfunction observed in young diabetic women. Similarly, pituitary function as assessed by basal gonadotrophins and gonadotrophin-releasing hormone (GnRH)-stimulated gonadotrophin relea se appears to be normal in young women with IDDM. Moreover, although t here has been some suggestion that pituitary function may decline with increasing duration of diabetes, this issue has not been thoroughly i nvestigated. It appears that the oligo/amenorrhea noted in IDDM is pri ncipally hypothalamic in origin and may represent intermittent (and pe rhaps reversible) failure of the GnRH pulse generator, similar to the situation observed in women who engage in endurance training or who su ffer from anorexia nervosa. Although the exact pathophysiological mech anisms that subserve dysfunction of the GnRH neuronal system are not w ell understood, attention has focused on increased central opioidergic activity, increased central dopaminergic activity, and central glucos e deprivation. In this era of emphasis on tight glycaemic control and its impact in preventing diabetes complications, the consequences of I DDM on reproductive potential appear to be important and must be inclu ded in future investigative efforts.