Abstract: Objective: To study the clinical risk factors of insulin resistance (IR) in patients with polycystic ovary syndrome (PCOS) and normal body mass index (BMI). Methods：A total of 203 PCOS patients with normal BMI from our hospital, from March 2018 to May 2019, were included in this study. According to the homeostasis model assessment-insulin resistance index (HOMA-IR), the patients were divided into two groups: the observation group (PCOS with normal BMI and HOMA-IR≥2.69, n=50); the control group (PCOS with normal BMI and HOMA-IR＜2.69, n=153 cases). The clinical characteristics, sexual hormone levels and glycolipid metabolism of the two groups were compared. The correlation between clinical characteristics, sex hormone levels, lipid metabolism and HOMA-IR was analyzed. The clinical risk factors related to IR were analyzed by multivariate Logistic regression. Results：The levels of WC, HC, WHR, TG, LDL-C, and UA in the observation group were significantly higher than those in the control group, and the levels of FSH, SHBG and HDL-C were significantly lower (all P＜0.05). The levels of WC, HC and TG were positively correlated with HOMA-IR (all P＜0.05), and the levels of WHR and LDL-C were weakly positively correlated (both P＜0.05), while the levels of SHBG and HDL-C were negatively correlated with HOMA-IR (both P＜0.05). WC is the risk factor of inducing IR in PCOS patients with normal BMI, and HDL-C is the protective factor of preventing IR in PCOS patients with normal BMI (both P＜0.05). Conclusions：WC as a risk factor can induce IR in those PCOS patients with normal BMI, and HDL-C acts as a protective factor.

Key words: Polycystic ovary syndrome；, Insulin resistance；, Body mass index；, Logistic models；, Gonadal steroid hormones