FGF21 and type 2 diabetes mellitus: Although the roles of Serpina11, Cdh16, Lrrc27, and Lrrc66 in regulating islet function remain unclear, Acod1 is known to be important in modulating the immune system and mitochondrial function [116,117,118], and Fgf21 can protect against type 2 diabetes in mice by increasing insulin expression and secretion [119,122].