Relationship between bone mineral density and insulin resistance in polycystic ovary syndrome

The aim of the present study was to evaluate whether there is a relationship between bone mineral density (BMD) and insulin resistance and hyperinsulinemia in women with polycystic ovary syndrome (PCOS). The study consisted of 28 amenorrheic women with PCOS and 11 amenorrheic women without PCOS. Fifteen healthy women with normal ovulatory function, matched for age and body mass index (BMI), served as controls. BMD was measured at the lumbar spine and left femoral neck with dual-energy X-ray absorptiometry. Blood samples were obtained to measure serum levels of insulin, follicle-stimulating hormone, luteinizing hormone, sex hormone-binding globulin (SHBG), total and free testosterone, androstenedione and estradiol by radioimmunassay. Insulin resistance was estimated by the in sulin tolerance test (ITT), and K(ITT) was taken as the insulin sensitivity index. In the PCOS group, K(ITT) was significantly lower and insulin levels were higher than in either of the control groups (P < 0.001). BMD in the PCOS group was lower than in the healthy group and higher than in the amenorrheic control group (P < 0.05). In the PCOS group, there were positive correlations of BMD of the lumbar spine with insulin (r = 0.42: P < 0.05) and negative correlations of BMD with K(ITT) (r = -0.58; P < 0.001) and SHBG (r = -0.38; P < 0.05). The inverse association of BMD and K(ITT) was independent of BMI, insulin, SHBG, androstenedione, and free testosterone. In conclusion, insulin resistance and hyperinsulinemia in women with PCOS may be a relative protective factor against bone mineral loss.