Given the role of GLP-1 in glycaemic control, the anti-apoptotic, growth-stimulating and insulin secretion-promoting effects on pancreatic β-cells, the ability to re-sensitize the cellular insulin-signaling, minor side effects, good tolerance by normoglycemic patients and the fact that GLP-1 does not desensitize, synthetic GLP-1R agonists have been on the market for decades to treat type 2 diabetes mellitus (T2DM) or, more recently, to improve weight loss (Drucker, 2018). This evidence concerns the gene GCG and diabetes mellitus.