Demodex parasites may cause skin and eyelash lesions by settling on the pilosebaceous unit. This parasite plays a role in the pathophysiology of acne in polycystic ovarian syndrome (PCOS). We aimed to examine the relationship between Demodex folliculorum and blood glucose control in patients with PCOS with skin and eyelash lesions. Forty-four patients with PCOS with skin lesions were enrolled in the study. At least two specimens were taken from the skin lesions using the standard method and at least six epilated eyelashes were taken from both eyes under a biomicroscope and evaluated using a light microscope. The demographic characteristics, body mass index (BMI) and clinical parameters of the patients were recorded. Demodex folliculorum was present at a rate of 59.1% in the skin lesions of the patients with PCOS, 40.9% in eyelash samples and 43.18% in both skin and lashes. Homeostasis model assessment of insulin resistance (HOMA-IR), glycosylated haemoglobin (HB A1c) concentrations, and BMIs were significantly higher in the patients who had D. folliculorum in skin samples than in those without (p = .010, p = .007 and p = .02). Impaired glucose regulation may explain the pathophysiology of the increased D. folliculorum presence in the skin lesions of patients with PCOS.Impact statement What is already known on this subject? Although several studies on Demodex folliculorum and PCOS have been conducted, we have not yet found a study that examines D. folliculorum parasites in the eyelashes and skin correlating with glucose regulation in PCOS. This study presents new information about the relationship between the presence of D. folliculorum and impaired glucose regulation in women with PCOS. What do the results of this study add? D. folliculorum is seen more commonly in skin lesions in patients with PCOS with impaired blood glucose regulation.