In contrast, RBP4 and retinol levels were higher in subjects with MetS vs. subjects without MetS (Figure 1B; RBP4: 41.38 ± 7.98 mg/L in subjects with MetS and 37.48 ± 8.48 mg/L in subjects without MetS, p = 0.041; retinol: 2.37 ± 0.50 μmol/L in subjects with MetS vs. 2.14 ± 0.46 μmol/L in subjects without MetS, p = 0.038). Here, RBP4 is linked to metabolic syndrome.