INS and type 2 diabetes mellitus: The potential targeting signaling pathways and targets of BAs and their derivatives in improving T2DM include: FGF15/19 regulates hepatic glucose and lipid metabolism by PPARγ, ERK signaling pathways and CREB6 dephosphorylation (Potthoff et al., 2011); FGF21 enhances insulin sensitivity by Mtorc1 signaling pathway (Pandak and Chiang, 2019) and stimulating APN secretion (Holland et al., 2013).