INS and polycystic ovary syndrome: Polycystic ovary syndrome (PCOS) is a type of reproductive disease that affects 5–18% of women worldwide who are of reproductive age.454 Interestingly, patients with PCOS are frequently associated with metabolic syndrome, such as obesity, dyslipidemia, impaired glucose tolerance or increased fasting insulin,455 which is closely linked to an abnormal gut microbiome.