GCG and type 2 diabetes mellitus: Glucagon-like peptide 1 (GLP-1)-based therapies including dipeptidyl peptidase-4 inhibitors (DPP-4Is) and GLP-1 receptor agonists (GLP-1Ras such as liraglutide), have been widely used for type 2 diabetes by improving pancreatic islet cell function, and reducing glucagon secretion7–10.