For example, metformin may alleviate abnormal visfatin levels in PCOS patients by increasing peripheral insulin sensitivity and thereby decreasing the IR-induced hyperinsulinemia, which, in turn, may lower visfatin secretion because insulin and glucose affect visfatin secretion via the phosphatidylinositol 3-kinase/protein kinase B pathway (55). Here, NAMPT is linked to polycystic ovary syndrome.