The rapid increasing prevalence of metabolic syndrome, T2DM, and NASH constitutes great burden on global public health, which need effective intervention to prevent them from developing into serious diseases like cardiovascular disease, stroke, and liver cirrhosis, etc. Emerging evidence demonstrates that circulating FGF21 can be used as a predictor or biomarker of some metabolic diseases such as diabetes, and CAD, because of its aberrantly increasing level. Here, FGF21 is linked to diabetes mellitus.