The unadjusted serum FGF21 levels with MetS showed that FGF21 increased per 1 pg/mL (odds ratio (OR): 1.008, 95% CI: 1.003–1.012, P=0.001) increased the 0.8% risk of MetS in patients with T2DM. This evidence concerns the gene FGF21 and type 2 diabetes mellitus.