The purpose of this study is to investigate whether higher insulin resistance in young women with Polycystic ovary syndrome (PCOS) is associated with reduced cerebral metabolic rate of glucose (CMRglu). Brain volumes using magnetic resonance imaging (MRI) and quantitative cerebral glucose uptake using dynamic positron emission tomography (PET) were obtained. The potential relationships between anatomical and functional cerebral parameters and insulin resistance were assessed with the updated homeostasis model assessment (HOMA2-IR).