NAMPT and obesity due to melanocortin 4 receptor deficiency: Since many covariates (such as obesity, metabolic syndrome) could affect visfatin levels, the relevant confounding variables (sex, age, BMI, BUN, Cr, FBG, PBG, HbA1C, HOMA-IR, TG, TC, HDL-C, LDL-C) were entered in the full regression model.