GCG and diabetes mellitus: Since the launch of exenatide, the first glucagon-like peptide-1 (GLP-1) receptor agonist (GLP-1 RA) approved by the United States Food and Drug Administration (FDA) for the management of type 2 diabetes mellitus (T2DM) in the United States in 2005 [1], several other medications in this class have been approved not only for T2DM but for other clinical indications.