Interestingly, DPP4 inhibitors including Sitagliptin, Teneligliptin, and Anagliptin that are used for the treatment of type 2 diabetes mellitus (T2DM, see below) were shown to have a negative impact on T-cell receptor signaling, T-cell activation, and proliferation in ex vivo analyses [62]. This evidence concerns the gene DPP4 and diabetes mellitus.