Evidence that insulin and androgens may participate in the regulation of serum leptin levels in women

Objective: Although serum leptin is principally influenced by body mass, to understand the role of insulin and androgens in the regulation of serum leptin in normal weight women. Design: Prospective observational study. Setting: Academic practice in reproductive endocrinology. Patient(s): Twenty- one women with polycystic ovary syndrome (PCOS) of normal body weight, 8 apparently normal women with polycystic-appearing ovaries (PAO), and 21 normal women. Intervention(s): Fasting blood levels of luteinizing hormone, follicle-stimulating hormone, testosterone (T), unbound T, dehydroepiandrosterone sulfate (DHEAS), insulin, insulin growth factor- binding protein-1 (IGFBP-1), and leptin. Main Outcome Measure(s): Comparisons of measured hormones in the different groups and correlative analysis Result(s): Women with PCOS had higher levels of serum luteinizing hormone, T, unbound T, DHEAS and insulin, and lower levels of IGFBP-1 compared with the normal controls, but they had similar leptin levels. Normal women with PAO had increased levels of insulin and leptin compared with controls, whereas IGFBP-1 was lower in PAO. In normal weight women with PCOS and PAO, leptin correlated positively with body weight and insulin, and negatively with IGFBP-1 and DHEAS. Conclusion(s): In normal weight patients serum leptin levels may be regulated in part by insulin. Androgens, on the other hand, may play a role in suppressing serum leptin.