Glucagon is a hormone secreted by pancreatic islet alpha cells, and its main role is to raise blood glucose, while more clinical attention is paid to pancreatic islet beta cells, which secrete insulin. Glucagon and insulin are in relative balance, with insulin mainly lowering blood glucose and glucagon mainly raising blood glucose. Once the secretion of insulin increases, the secretion of glucagon will also increase, so that the blood glucose can be kept within the normal range smoothly, such as fasting fluctuation around 3-6mmol/L and postprandial fluctuation around 4-8mmol/L, so as to avoid various effects on tissues caused by too high or too low blood glucose.