INS and metabolic syndrome: The definition of metabolic syndrome (MetS) includes five criteria: (1) central obesity, defined as a large waist circumference (WC), an elevated waist–hip ratio (>0.90 for females and >0.85 for males), or a body mass index (BMI) above 30 kg/m; (2) raised blood pressure; (3) dyslipidemia, i.e., elevation of total cholesterol (TC), low-density lipoprotein (LDL), and/or triglycerides (TG), and low high-density lipoprotein cholesterol (HDL-C); (4) raised fasting plasma glucose; and (5) raised fasting serum insulin.