With regard to GIP, although overall secretion as assessed from a meta-analysis of nutrient-stimulated secretion (oral glucose or mixed meals) appears to be similar for those with NGT and those with type 2 diabetes (Fig. 2d), there were non-significantly higher plasma GIP responses in type 2 diabetes for those with a higher BMI (Fig. 2e), who were younger (Fig. 2f) and with higher HbA1c levels (Fig. 2g) [9]. Here, GIP is linked to type 2 diabetes mellitus.