Evidence for competing effects of body mass, hyperinsulinemia, insulin resistance, and androgens on leptin levels among lean, overweight, and obese women with polycystic ovary syndrome

Objective: To evaluate the relationships between leptin, body composition, insulin resistance, androgens, and reproductive indices among women with polycystic ovary syndrome (PCOS). Design: Matched case-control study. Setting: Academic reproductive endocrine practice; school of public health. Patient(s): Forty-six Caucasian women with PCOS and 46 population-based controls matched by age and body mass index (BMI). Intervention(s): None. Main Outcome Measure(s): Leptin, insulin, androgenic hormones, body composition parameters; reproductive parameters. Result(s): Overall, leptin levels among women with PCOS did not differ significantly from those of control women (20.4 +/- 14.9 vs. 21.9 +/- 14.3 ng/mL). However, within the lowest BMI tertile, women with PCOS had significantly lower leptin levels (9.6 vs. 18.3 ng/mL), comparable insulin, and higher testosterone concentrations than controls of similar body mass. Within the overweight and obese subgroups, both insulin and testosterone levels were increased among women with PCOS; leptin levels, although higher among obese cases, were not statistically different than those in controls. Conclusion(s): Below a certain BMI, hyperandrogenic women with PCOS have lower leptin levels than controls. Conversely, overweight and obese PCOS subjects appear to produce insufficient leptin for a given fat mass, relative to the degree of hyperinsulinemia, potentially because of the competing effects of adipocyte insulin resistance and androgens on leptin. (C) 2002 by American Society for Reproductive Medicine.