Abstract Objective To investigate the effects of metformin (MET) monotherapy and pioglitazone plus MET (PIOMET) therapy on gonadal and metabolic profiles in normal-weight women with polycystic ovary syndrome (PCOS). Methods Sixty normal-weight women with PCOS were recruited between January and September 2022 at the Shengjing Hospital of China Medical University. They were randomly assigned to the MET or PIOMET groups for 12 weeks of MET monotherapy or PIOMET therapy. Anthropometric measurements, menstrual cycle changes, gonadal profiles, and the oral glucose insulin-releasing test (OGIRT) were performed at baseline and after the 12-week treatment. Results Thirty-six participants completed the trial. MET and PIOMET therapies improved menstrual cycles after the 4- and 12-week treatments; however, there was no statistical difference between the two groups. PIOMET therapy improved luteinizing hormone (LH), luteinizing hormone/follicle stimulating hormone (LH/FSH) ratio, and free androgen index (FAI) levels after the 4-week treatment, whereas MET monotherapy only improved total testosterone (TT) levels compared to baseline (P