INS and diabetes mellitus: It mainly acts on the liver through the FGF19-β-Klotho-FGFR4 pathway, regulating bile acid synthesis and lipid metabolism; fGF21-β-Klotho-FGFR1c pathway promotes glucose uptake, enhances insulin sensitivity and improves lipid mass spectrometry in fat and liver (19, 46).FGF21 analogues have entered clinical trials in diabetes research, showing improved effects on blood glucose and lipid metabolism, and β-Klotho is a central molecule necessary for this signal transduction (47).