In fact, in an experiment with co-infusion, the suppression of glucagon secretion by GLP-1 was obliterated by co-infusion with GIP, perhaps in agreement with the observation that GIP, if anything, stimulates glucagon secretion, particularly in T2DM patients, an effect that might actually contribute to the development of hyperglycemia (29). This evidence concerns the gene GLP1R and type 2 diabetes mellitus.