Therapeutic treatment with the AngII subtype AT1-receptor-blockers, statins, and organic nitrates that have antioxidant effects, significantly improves the expression of GCH-1 or GTP cyclohydrolase I enzyme which is a part of the folate and biopterin biosynthesis pathway that can normalize BH4 levels, revitalize eNOS, and improve endothelial function in pathological states such as diabetes, hypertension, atherosclerosis, and nitrate tolerance [85,86]. Here, GCH1 is linked to diabetes mellitus.