Impact of insulin and body mass index on metabolic and endocrine variablesin polycystic ovary syndrome

To assess the differential impact of the insulin secretory pattern and obes ity on the endocrinometabolic features of the polycystic ovary syndrome (PC OS), we studied 110 PCOS women. Patients underwent a gonadotropin-releasing hormone (GnRH) test, an oral glucose tolerance test (OGTT), and basal eval uation of hormonal and biochemical parameters. Basal androgens end lipids, basal and stimulated gonadotropins, insulin, and glucose levels were measur ed. Patients were classified into four groups according to the body mass in dex (BMI) and insulin secretion: normoinsulinemic-lean ([NL] n = 24), normo insulinemic obese ([NO] n = 24), hyperinsulinemic lean ([HF] n = 17), hyper insulinemic obese ([HO] n = 45). HL patients showed a higher luteinizing ho rmone (LH) area under curve (AUC) after GnRH stimulus compared with NL pati ents (HL v NL, 4,285 +/- 348 v 3,377 +/- 314 [U/L . 120 min, P < .05), wher eas we failed to find a statistically significant difference in a similar c omparison among obese subjects (HO v NO, 3,606 +/- 302 v 3,129 +/- 602 IU/L . 120 min). A trend toward increased plasma testosterone and decreased sex hormone-binding globulin (SHBG) was found in relation to hyperinsulinemia and obesity, thus resulting in a higher free androgen index (FAI) in groups HL and NO versus NL (HL, 5.54 +/- 0.51; NO, 5.64 +/- 0.49; NL, 4.13 +/- 0. 33; P < .05 and P < .01, respectively). The presence of both exaggerated in sulin secretion and obesity resulted in a synergistic additive effect on th e FAI in the HO group (6.81 +/- 0.34). Concerning the lipoprotein lipid pro file, the NL group showed lower plasma triglyceride levels compared with th e other three groups, whereas no significant differences were found for non esterified fatty acid (NEFA) concentrations. Higher low-density lipoprotein cholesterol (LDL-C) and very-low-density lipoprotein cholesterol (VLDL-C) and lower high-density lipoprotein cholesterol (HDL-C) levels were found in the obese groups compared with the lean counterparts, whereas the same par ameters did not significantly differ in a comparison between normoinsulinem ic and hyperinsulinemic groups. In conclusion, our data suggest an importan t role of hyperinsulinemia in the LH response to a GnRH stimulus and an ind ependent and synergistic additive effect of obesity and hyperinsulinemia on the FAI in PCOS. Copyright (C) 1999 by W.B. Saunders Company.