GCG and type 2 diabetes mellitus: In patients with T2D, GIP-stimulated glucagon secretion observed in healthy participants is not maintained.34,64 However, the coexistence of GIP and GLP-1 in patients with T2D produces glucagon concentrations akin to control conditions.65 DPP-4 inhibitors enhance GIP and GLP-1, which are physiologically derived in the gut in response to oral nutrient intake, thus acting similarly to the coexistence of GIP and GLP-1 (Figure 3).64,66