INS and type 2 diabetes mellitus: T2DM, type 2 diabetes; T, tertile; WC, waist circumference; BMI, body mass index; BF, body fat; FPG, fasting plasma glucose; HbA1c, glycated hemoglobin; SI, serum insulin; TC, total cholesterol, TG, triglycerides; HDL, high-density lipoprotein; LDL, low-density lipoprotein; Vit.