However, in patients with T2D, normalization of blood glucose through a 6 h GLP-1 infusion is not capable of restoring GIP responsiveness [156], and the insulin response to GLP-1 and GIP co-infusion is indistinguishable from GLP-1 treatment in individuals with obesity during isoglycemic i.v. glucose infusion [181]. Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.