For the treatment of adult patients with type 2 diabetes (T2D), SIT, a dipeptidyl peptidase-4 inhibitor, is approved in more than 130 countries throughout the world as monotherapy and in combination with other anti-hyperglycemic drugs [69], along with MEL against the SARS-CoV-2 virus. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.