To evaluate the effects of sitagliptin on the metabolic indices and hormone levels in patients with polycystic ovary syndrome (PCOS). PubMed, EMBASE, Web of Science, Cochrane Library, WanFang Data, and China National Knowledge Infrastructure (CNKI) were searched for randomized controlled trials (RCTs) published up to March 2022. Eligible studies were identified based on the inclusion criteria. The primary outcomes included the homeostasis model assessment of insulin resistance (HOMA-IR), body mass index (BMI), and total testosterone level (TT). Other outcomes included levels of sex hormones, glucose, and lipid metabolism. Forty-five studies were initially identified, and 6 RCTs with 394 patients were finally included in this study. The meta-analysis results suggest that sitagliptin improved HOMA-IR (WMD =  - 0.35; 95% CI (- 0.62, - 0.08); P = 0.01), BMI (WMD =  - 1.27; 95% CI (- 1.76, - 0.77); P < 0.00001), TT (SMD =  - 0.66; 95% CI (- 1.25, - 0.07); P = 0.03), and HDL-C (SMD = 0.11; 95% CI (0.03, 0.18); P = 0.005). No significant differences were observed between the sitagliptin and control groups in other outcomes and in terms of adverse events. Evidence from meta-analyses suggests that sitagliptin was superior in improving insulin sensitivity, total serum testosterone, high-density lipoprotein, and body mass index. However, due to the limitations of published studies, it is difficult to draw a definite conclusion. Larger, higher-quality studies are needed to evaluate the efficacy of sitagliptin in women with PCOS.