Relationship between insulin resistance and gonadotropin dissociation in obese and nonobese women with polycystic ovary syndrome

OBJECTIVE: To test the interdependence between insulin resistance (IR) and gonadotropin dissociation (GD) in polycystic ovary syndrome (PCOS). DESIGN: Cross-sectional prospective study. SETTING: Clinical research center. PATIENT(S): Thirty-two PCOS patients aged 19-34 years; 16 obese (BMI > or = 27) and 16 nonobese (BMI < 27). INTERVENTION(S): A 75-g oral glucose tolerance test (OGTT) and a 100-microg i.v. GnRH test were performed on different days. Blood was taken at 0, 30, 60, 90, 120, and 180 minutes in each test. Serum glucose, insulin, LH, and FSH were measured. MAIN OUTCOME MEASURE(S): Area under the curve was calculated for glucose, insulin, and glucose-to-insulin ratio (GIR), and for LH, FSH, and LH-FSH ratio. RESULT(S): Glucose, insulin, and GIR were not modified significantly during the GnRH test, nor LH, FSH and LH-FSH ratio throughout the OGTT. There were no significant differences in GIR response of patients with and without GD, nor in LH-FSH ratio of patients with and without IR, after OGTT and GnRH test. However, obese patients with IR had a significantly larger (P<.04) area under the curve for LH-FSH ratio than those without IR after GnRH test, but not after OGTT test. CONCLUSION(S): Insulin resistance and GD do not appear to be related events in PCOS, suggesting that each one might be determined by different genetic disorders. However, IR can affect GD after chronic stimulation in obese patients.