DPP4 and type 2 diabetes mellitus: In line with this, mice with targeted downregulation of DPP-IV showed higher plasma levels of GIP and GLP-1, increased insulin secretion, and reduced glucose release (114), whereas DPP-IV inhibitors were reported to reduce HbA1C levels by 0.7% in T2D patients undergoing metformin therapy (115) (Figure 1).