Well-controlled type 2 diabetes patients have intact GLP-1 response to glutamine ingestion [7] and glutamine (30 g) or glutamine (15 g) in combination with the DPP-4 inhibitor sitagliptin (100 mg) decreases postprandial glycaemia and increases circulating insulin and GLP-1 when administered with a meal [8]. This evidence concerns the gene GCG and type 2 diabetes mellitus.