GCG and type 2 diabetes mellitus: This study evaluated the relationship between postprandial GIP and glucagon responses to a mixed meal in T2D and to intraduodenal fat and glucose infusion in healthy and/or T2D individuals.<h4>Materials and methods</h4>Data were analysed from three clinical studies: mixed-meal testing in T2D (n = 79), intraduodenal fat infusion (2 kcal/min over 120 min) in T2D (n = 15) and intraduodenal glucose infusion (2 kcal/min over 60 min) in health and T2D (n = 10 each).