Abstract Introduction: Polycystic ovary syndrome (PCOS) is an endocrine, reproductive and metabolic disorder and a major cause of infertility in women. Testosterone propionate (TP) is used to induce PCOS in rats. High calorie diet causes metabolic changes, oxidative stress and PCOS. Sitagliptin (STG) is an inhibitor of dipeptide peptidase (DPP) 4 enzyme used in the treatment of type 2 diabetes. Objective: The aim of the study is to investigate the effect of high fat, high fructose diet (HFFD) on TP induced PCOS rats and the role of STG on oxidative stress and inflammation in PCOS. Materials and methods: PCOS was induced by administration of TP to normal pellet and HFFD fed rats for 43 days. STG (i.p.) was given for the last 15 days to both groups of rats. Vaginal smear, parameters of oxidative stress, antioxidants and inflammation (TNF-α and IL-6) in ovary were analyzed. Results: Vaginal smear from TP rats consisted of persistent leucocytes, a characteristic of PCOS. All the TP administered rats registered significanty elevated levels of glucose, lipids, oxidative stress and inflammatory markers, and reduced levels of antioxidants compared to CON rats. STG treatment to PCOS rats reduced hyperglycemia and hyperlipidemia, oxidative stress and inflammation and improved estrus cycle. Conclusion: High energy diet aggravated TP-induced changes in oxidative stress and inflammatory cytokines in ovary. STG recuperated the changes induced by TP, suggesting that STG holds potential for PCOS management.