Glucagon plays a crucial role in glucose metabolism by promoting the release of glucose from the liver into the bloodstream, especially when blood sugar levels drop. It acts as a counter-regulatory hormone to insulin, which lowers blood sugar levels. When glucose is needed, glucagon stimulates glycogenolysis (breakdown of glycogen) and gluconeogenesis (production of glucose from non-carbohydrate sources). This mechanism ensures a stable supply of glucose for energy, particularly during fasting or intense exercise periods.