Abstract:Objective To investigate the effects of metformin alone or the fixed-dose combination of pioglitazone and metformin in treating infertile patients with insulin resistance polycystic ovary syndrome (PCOS). Methods A total of 77 infertile patients with insulin resistance PCOS were selected as research objects from January 2015 to June 2017 in our reproductive medicine center, and randomly divided into the observation group (including 39 cases treated with the fixed-dose combination of pioglitazone and metformin) and the control group (including 38 cases treated with metformin). The insulin resistance index (HOMA-IR), levels of sex hormone, ovulation rate and pregnancy rate were compared between the two groups. Results After 3 month's treatment, HOMA-IR, the levels of testosterone (T), luteinizing hormone (LH), and LH/FSH in the observation group were significantly decreased as compared to those in the control group (P?0.05); there was no significantly difference of the levels of follicle-stimulating hormone (FSH) and estradiol (E2) between two groups (P?>?0.05). The number of mature follicles, ovulation rate and pregnancy rate in the observation group were significantly higher than in the control group (P?0.05). Furthermore, HOMA-IR were negatively associated with the number of mature follicles (r?=?-0.491, P?=?0.000), ovulation rate (r?= -0.331, P?=?0.003) and pregnancy rate (r?=?-0.318, P?= 0.005) after treatment. Conclusions The fixed-dose combination of pioglitazone and metformin was more effective than metformin in decreasing insulin resistance, improving levels of sex hormone, and increasing ovulation and pregnancy rates in treating infertile patients with insulin resistance PCOS.