Aim: Since it has been established that DPP-4 and GLP-1 are important incretins linked to the pathogenicity of diabetes mellitus, with their involvement in periodontal disease having been proven, the present review aims to update the recent data regarding these incretins’ roles in patients with periodontitis and diabetes, with an emphasis on patients who have both diabetes mellitus and periodontitis. This evidence concerns the gene DPP4 and diabetes mellitus.