Diabetes significantly impaired PHE-induced vasoconstriction and Ach-induced vasorelaxation (P < 0.001), reduced NO bioavailability and H2S production (P < 0.001), SOD activity, and GPX1 protein expression (P < 0.001), and increased malondialdehyde content and NADPH oxidase subunits, and CSE and CBS protein expression (P < 0.001). Here, GPX1 is linked to diabetes mellitus.