In 2016, we published the first report of a markedly prolonged clinical remission phase (up to 4 years) and preserved beta-cell function in two patients with T1D who received the dipeptidyl peptidase-4 inhibitor (DPP-4i) sitagliptin (100 mg/day) plus vitamin D3 (5,000 IU/day) (18). Here, DPP4 is linked to type 1 diabetes mellitus.