GCG and type 2 diabetes mellitus: Currently, synthetic peptides are commonly used as treatments for T2DM with insulin analogues, and more recently incretin mimetics, acting as either analogues (e.g., GLP-1 and GIP analogues) or antagonists (e.g., GLP-1 receptor antagonists) of endogenous human hormones forming the core of a number of modern antidiabetic drugs [9].