The application of insulin sensitizers in PCOS patients in recent years has significantly reduced androgen levels and improved symptoms, as well as demonstrating the role of insulin resistance in the pathogenesis of PCOS. There is increasing evidence that insulin resistance plays an equally important role in the etiology and outcome of PCOS, and hyperinsulinemia in PCOS patients is receiving increasing attention from physicians and patients. Insulin resistance and hyperinsulinemia is one of the basic features of abnormal glucose metabolism in PCOS patients, of which the prevalence of hyperinsulinemia is about 57% in obese patients and more than 40% in non-obese patients. the prevalence of obesity in PCOS patients is 25.7%. insulin in PCOS patients. The clinical characteristics of resistance: 1, obese and non-obese patients have insulin resistance and hyperinsulinemia, but obesity factors significantly aggravate insulin resistance. 2. Patients with different degrees of reproductive dysfunction have different degrees of insulin resistance. Insulin resistance in patients with scanty menstruation and anovulation is more severe than in some patients with normal menstruation and ovulation; insulin resistance in obese patients is heavier than in non-obese patients. Both obese and non-obese PCOS patients have insulin resistance, and obesity is an important risk factor for insulin resistance, and insulin resistance with secondary hyperinsulinemic state is considered to be a common feature of PCOS. The occurrence of insulin resistance in patients with PCOS cannot be completely explained by obesity, but obesity can aggravate insulin resistance. The results of this investigation showed that the prevalence of obesity and insulin resistance were 25.7% and 45.7%, respectively. European and American literature reported that the prevalence of obesity and insulin resistance in PCOS is 50-70%. Because of the differences in ethnicity and dietary habits between Europeans and Asians, there are differences in the prevalence and diagnostic criteria for obesity. Obese PCOS patients are more likely to have abnormalities in glucose and insulin metabolism. Obesity can aggravate not only insulin resistance but also reproductive dysfunction. The possible mechanisms are as follows: 1, obesity aggravates hyperinsulinemia, excess insulin can promote the formation of ovarian follicular cysts, stimulate ovarian follicular membrane cells to produce steroids and androgens, resulting in ovarian local androgen overproduction, leading to follicular atresia and anovulation; 2, obese PCOS patients have reduced sex hormone binding protein activity and increased serum free testosterone levels, further aggravating androgenic ovulation disorders 3, adipose tissue is an important site of steroid hormone metabolism, obese PCOS patients androgens in adipose tissue into estrogen increased estrogen cyclic changes disappear, aggravating ovulation disorders. Therefore, for obese PCOS patients to advocate their active weight control, improve hyperinsulinemia, break the vicious circle between endocrine metabolism, which is important for the improvement of patient symptoms and prevention of long-term complications.