Serum leptin levels correlate with clinical and biochemical indices of insulin resistance in women with polycystic ovary syndrome

Abstract

Objectives: To compare serum leptin levels in women with polycystic ovary syndrome (PCOS) and healthy subjects, and to evaluate the relationship between leptin concentration and insulin resistance.

Methods: Forty-five women with PCOS and 20 controls were included in the study. Serum levels of leptin, testosterone, immune-reactive insulin (IRI), sex hormone-binding globulin, dehydroepiandrosterone sulfate, cortisol, LH and FSH were measured. Free androgen index (FAI) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. Body mass index (BMI) and waist-to-hip ratio (WHR) were assessed.

Results: Serum leptin levels in PCOS patients were higher than in the control group independently of BMI, WHR and waist circumference. In PCOS patients there was a strong positive correlation between leptin and IRI (r = 0.592, p < 0.01) on the one hand, and leptin and HOMA-IR, on the other (r = 0.637, p < 0.01). In PCOS patients with more pronounced insulin resistance (IR) the correlation between leptin levels and HOMA-IR is independent of BMI, WHR and waist circumference. We did not find any correlation between leptin and other hormonal indices in PCOS patients.

Conclusions: Our study confirms the existence of a significant positive correlation between serum leptin levels and clinical and hormonal indices of IR. The hyperleptinaemia is probably due to leptin resistance and may be characteristic of the syndrome. The lack of correlation with other hormonal parameters is probably due to the heterogeneity of the PCOS group.