Catalase catalyzes the conversion of hydrogen peroxide to water and oxygen. Research studies show that overexpression of this antioxidant enzyme increases the ability of pancreatic ?-cells to scavenge reactive oxygen species (ROS), thereby protecting pancreatic ?-cells from oxidative stress. The pancreatic ?-cells overexpressing this enzyme are also protected from hydrogen peroxide-mediated lipotoxicity, providing further evidence for the importance of catalase in the pathogenesis of diabetes.