An acute glucose-lowering effect of DPP-4 inhibition in a rodent model of T2DM (the obese Zucker rat) was demonstrated when it was shown that a different inhibitor (isoleucine thiazolidide) reduced plasma DPP-4 activity and was associated with a larger insulin response and improved glucose tolerance after an oral glucose load (when endogenous GLP-1 secretion would be stimulated) (26). This evidence concerns the gene GCG and type 2 diabetes mellitus.