INS and polycystic ovary syndrome: TGF-β1 methylation rate was negatively correlated to fasting insulin (FINS) (R = -0.32, P = 0.012) and HOMA-IR (R = -0.28, P = 0.029) and positively correlated with age (R = 0.38, P = 0.0032). This hypomethylation may influence TGF-β1 gene expression and contribute to the development of IR, a prominent feature of PCOS.