This is in line with previous stimulation studies with concomitant GIP and GLP-1 infusion, where reduced GIP sensitivity was identified as the major factor responsible for ineffective late-phase insulin responses to glucose in T2D patients compared to healthy controls (despite a normalizing effect of GLP-1 infusion on late-phase insulin release), while both incretins were unable to restore early-phase insulin responses mostly in all forms of diabetes (5, 6). Here, GIP is linked to diabetes mellitus.