FGF21 and type 2 diabetes mellitus: As shown in Figure 3, the ROC curve depicted that the area under the curve (AUC) of serum FGF21 in predicting the occurrence of CAD in T2DM men was 0.625 (95% CI: 0.576-0.674), the sensitivity was 0.472, the specificity was 0.723, and the Youden index was 0.195.