Prevalence and degree of insulin resistance in Chinese Han women with PCOS: Results from euglycemic-hyperinsulinemic clamps

Objective The euglycemic-hyperinsulinemic clamp is the gold standard to evaluate insulin resistance (IR), but there are only a few studies on the prevalence of IR in Chinese Han women with polycystic ovary syndrome (PCOS). This study investigated: (a) the prevalence of IR in Chinese Han women with PCOS by clamp, (b) the degree of reduction in insulin sensitivity (IS) and the contribution of body mass index (BMI). Design Retrospective cross-sectional analysis. Patients Chinese Han women with PCOS (n = 448) visiting the Department of Endocrinology or the Department of Obstetrics and Gynaecology of the First Affiliated Hospital of Chongqing Medical University. Chinese Han women without PCOS (controls) from the same area (n = 40). Measurements Clamp-measured IS, age, BMI, and total testosterone. Results The prevalence of IR and reduction in IS were 56.3% and 30.3%, respectively, in Chinese Han women with PCOS (both P < 0.001). The inherent reduction in IS was 18.8% in lean women with PCOS and BMI independently reduced IS by 37.9% in obese women with PCOS. The prevalence of IR estimated by homeostatic model assessment (HOMA) was lower than that determined by clamp. The multivariable analysis showed that IR by clamp (R-2 = 0.48, P < 0.001) was independently associated with BMI (beta = -0.52, P < 0.001), waist-hip ratio (beta = -0.23, P < 0.001), total testosterone (beta = -0.07, P = 0.045) and age (beta = 0.17, P < 0.001), while IR by HOMA was only associated with BMI (R-2 = 0.25, beta = 0.50, P < 0.001). There were no differences in BMI groups distribution, HOMA-IR and M values among the four PCOS subtypes (all P > 0.05). Conclusions 56.3% of Chinese Han women with PCOS had IR and their reduction in IS was 30.3%. Obesity exacerbated the reduction in IS. When being evaluated by HOMA, the prevalence and the risk factors of IR in Chinese women with PCOS were underestimated.