A possible mechanism for the increased risk of MetS due to cigarette smoking is that smoking causes higher fasting plasma cortisol concentrations, resulting in an increase in visceral adipose tissue.26 Smoking also causes deterioration of lipid metabolism via decreased lipoprotein lipase.27 In addition, some studies have demonstrated that smokers are insulin-resistant and hyperinsulinemic.27,28 Smoking is reported to cause systemic oxidative stress. Here, INS is linked to metabolic syndrome.