The protein encoded by this gene is the glucagon receptor, a member of the secretin receptor family of class B G-protein-coupled receptors (GPCRs). This receptor plays a critical role in maintaining blood glucose homeostasis by mediating the effects of glucagon, including stimulation of hepatic glycogenolysis and gluconeogenesis. This gene is expressed primarily in the liver and kidney but also in the heart, adrenal glands, pancreas, spleen, thymus, cerebral cortex, adipose tissue, and gastrointestinal tract. Mutations in this gene can impair glucagon signaling, leading to dysregulation of glucose metabolism and contributing to the development of non-insulin-dependent diabetes mellitus (type 2 diabetes). Such defects may result in altered glucose production, insufficient counter-regulation during fasting, and increased susceptibility to hyperglycemia. Inactivating mutations in this gene cause resistance to glucagon which is associated with Mahvash disease. [provided by RefSeq, Mar 2026]