The progression of carbohydrate metabolism disorders towards diabetes is associated with impaired compensatory insulin secretion due to increased apoptosis of pancreatic islet β cells, which is facilitated by both impaired GLP-1 secretion and increased release of pro-inflammatory cytokines and leptin by visceral adipose tissue, as well as increased glucagon secretion and increased hepatic glucose synthesis as well as progressive changes in skeletal muscle metabolism [42]. Here, GCG is linked to diabetes mellitus.