What hormone is responsible for increasing blood glucose levels during fasting?

Glucagon plays a crucial role in raising blood glucose levels, particularly during periods of fasting or when the body requires additional energy. It is produced by the alpha cells of the pancreas, and its primary function is to stimulate the liver to convert stored glycogen into glucose, which is then released into the bloodstream. This increase in blood glucose is essential for maintaining adequate energy supply to vital organs, especially the brain, which relies heavily on glucose as an energy source.

During fasting, when insulin levels are low, glucagon acts to counterbalance that by promoting glycogenolysis (the breakdown of glycogen) and gluconeogenesis (the production of glucose from non-carbohydrate sources). This mechanism ensures that the body maintains stable glucose levels even when food intake is absent, thus preventing hypoglycemia.

Understanding the role of glucagon is important in various contexts, including diabetes management, metabolic disorders, and nutritional physiology, as it demonstrates how the body regulates energy balance and responds to changes in food availability.