GCG and type 2 diabetes mellitus: As expected, linagliptin, a DPP4-inhibitor clinically used for treating T2D, highly increased the amount of active GLP-2 in all conditions (Figure 1B), in line with its activity to block cleavage of GLP-2 by DPP4, similar to its effect on GLP-1 secretion from human islets (6).