GCG and type 2 diabetes mellitus: Summarizes three studies (co-)authored by author. 1) assessed the impact of NAFLD on the incretin effect in patients with or without type 2 diabetes. 2) investigated the influence of cirrhosis on incretin physiology 3) examined the glucagonostatic effect of GLP-1 and its potential glucose- dependency in non-diabetic patients with NAFLD - excluded from this review as glucose-levels were kept at fasting levels.