Moreover, it should be highlighted that T1D is often accompanied by many abnormalities other than the loss and dysfunction of beta cells, including the dysfunction of glucagon-secreting pancreatic alpha cells [15], histological abnormalities of the exocrine pancreas [16], as well as increased serum activity of the enzyme dipeptidyl peptidase-4 (DPP-4) [17], among others. Here, DPP4 is linked to type 1 diabetes mellitus.