DPP4 and diabetes mellitus: The possible association between the use of dipeptidyl peptidase-4 (DPP-4) inhibitors - drugs approved for the treatment of type 2 Diabetes Mellitus - and an increased risk of developing BP has recently been reported in several studies [2,5,6,7]. DPP-4 inhibitors prevent the degradation of glucagon-like peptide 1 (GLP-1).