Effects of luteinizing hormone, insulin, insulin-like growth factor-I and insulin-like growth factor small binding protein 1 in the polycystic ovary syndrome

This study explores the clinical and endocrine implications of hyperinsulinaemia in the polycystic ovary syndrome (PCOS). Oral glucose tolerance tests were performed on 34 lean and 19 obese women with PCOS and on 13 lean women with normal ovaries. Insulin measurements were compared with basal gonadotrophins, androgens, insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein 1 (IGFBP-1). Unselected lean women with PCOS were found to have fasting hyperinsulinaemia and the raised serum insulin concentrations were associated with menstrual disturbance and hyperandrogenaemia. In addition, serum insulin concentrations in lean women with PCOS correlated positively with serum IGF-I and negatively with serum IGFBP-1 concentrations. Ovarian stimulation by insulin appears to be independent of luteinizing hormone (LH) and is an important feature in 30% of lean women with PCOS.