Glucagon receptor (GCGR) mediates the effects of glucagon in controlling glucose metabolism by initiating a cascade of events that regulate the amount of glucose released from the liver into the bloodstream. Glucagon generally functions as a counterregulatory hormone, opposing the actions of insulin, in maintaining the levels of blood glucose, particularly in patients with hypoglycemia. In patients with diabetes, excess glucagon secretion plays a primary role in the metabolic perturbations associated with diabetes, such as hyperglycemia. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804