Since glucagon-like peptide 1 (GLP-1) and its analogs were previously confirmed with an inhibitory effect on the neural inflammation and DPP-4 inhibitor can increase the endogenous GLP-1 availability, we investigated the effect of DPP-4 inhibitor on neural inflammation in diabetic rats to further reveal the mechanism of its protective effect on cognitive function damaged by diabetes. Here, DPP4 is linked to diabetes mellitus.