CAT and diabetes mellitus: The attenuation of oxidative stress and enhancement of an anti-oxidant response, as evidenced by decreased malondialdehyde (MDA) levels and increased glutathione (GSH) levels and superoxide dismutase (SOD) and catalase (CAT) activities, is at least partially responsible for the antidiabetic effect of H2 on DM [12,13,14,15,16,17].