DPP4 and type 2 diabetes mellitus: The hypoglycemic effect seen in the OGTT during the selection of a lead compound in the experiment on C57BL/6 mice (without T2DM and without concomitant insulin resistance) is most likely due to the action of 3 on free fatty acid receptor 1 (GPR40), trace amine-associated receptor 1, and to a lesser extent dipeptidyl peptidase 4 [29,30].