This mouse strain is generated through genetic engineering technology, replacing the coding region of the endogenous mouse glucagon receptor (Gcgr) gene with the human GCGR gene sequence. Based on the retention of mouse endogenous regulatory elements, this model expresses functional human GCGR protein in physiologically relevant cells and tissues (primarily the liver, but also including the pancreas, kidneys, etc.). Glucagon binds to and activates GCGR, playing a crucial role in maintaining blood glucose homeostasis, promoting hepatic glycogenolysis and gluconeogenesis, making it an important therapeutic target for metabolic diseases such as type 2 diabetes and non-alcoholic fatty liver disease (NAFLD/NASH). This humanized model allows candidate drugs targeting human GCGR (such as monoclonal antibodies, antagonists) to be accurately evaluated for their function, efficacy, and safety in immunocompetent mice, overcoming the data translation challenges caused by receptor species differences in traditional mouse models and significantly enhancing the predictive value of preclinical studies.