Subsequent studies in healthy individuals and those with T2DM demonstrated that the metabolite resulting from DPP4 cleavage is the primary circulating form of GLP-1-like immunoreactivity [27] and that this metabolite is rapidly formed following exogenous administration of GLP-1 in both healthy subjects and those with T2DM [28]. Here, DPP4 is linked to type 2 diabetes mellitus.