As the goal of FGF21 engineering was to improve biopharmaceutical properties of the protein while maintaining its in vivo potency, LY2405319 was profiled for bioactivity in cell culture studies and in mouse models of diabetes in a panel of in vitro and in vivo assays that have been previously established to characterize the effects of FGF21 [1], [18]–[21]. This evidence concerns the gene FGF21 and diabetes mellitus.