RBP4 and diabetes mellitus: Compared to patients in the first quartile of serum RBP4 level (reference group), those exposed to the second, the third, and the fourth quartiles had associated hazard ratios (HRs) of 2.38 [95% confidence interval (CI): 1.33–4.26], 2.35 (95% CI: 1.31–4.21), and 2.27 (95% CI: 1.28–4.04), respectively, for MACEs development after adjustment for age, sex, BMI, smoking, hypertension, diabetes mellitus, CKD, and the medication usage.