INS and Insulin resistance: Both insulin resistance and β-cell dysfunction have been demonstrated to be established pivotal mechanisms of MS [2, 26], and an impaired antioxidant defense system has been reported to contribute to the development of MS [4]; therefore, based on the finding of the multivariable logistic regression analysis in this study, we hypothesized that impaired insulin and β-cell dysfunction might mediate the effect of the decrease of SOD activity on the development of MS and its related metabolic abnormalities.