Multivariate forward stepwise linear regression analysis of the variables significantly associated with fasting serum FGF21 levels revealed that body fat mass (adjusted R2 change = 0.218, P=0.008) and log-TG (adjusted R2 change = 0.036, P < 0.001) positively correlated, whereas eGFR (adjusted R2 change = 0.033; P=0.013) negatively correlated with serum FGF21 levels in patients with T2DM. This evidence concerns the gene FGF21 and type 2 diabetes mellitus.