INS and gestational diabetes: Although insulin has been seemed as the gold standard for hyperglycemia treatment during pregnancy (Park et al., 2015), in this study, we demonstrated that MET promoted angiogenesis against GDM-induced impairment via enhancing Nrf2 expression and downregulating transcriptional factor p65, which could provide a new theoretical basis for the therapy of gestational diabetes, not only via controlling blood glucose levels, but also via improving endothelial dysfunction.