Novel insights into the physiological functions of glucagon

Abstract Discovered a hundred years ago, glucagon continues to amaze clinicians globally with its range of functions affecting the entire human physiology. Although initially it was considered just an opposer of insulin action, recent years have seen that glucagon has a plethora of effects on body metabolism. However, many aspects of the complex regulatory mechanisms of glucagon secretion and its impact on nutrient metabolism are yet to be clearly elucidated. Understanding the physiology of glucagon secretion and action is the key to the development of pharmacological agents which would impact on metabolic disorders. Glucagon secretion is regulated by a variety of factors, including meal type, paracrine hormone secretion from α and β cross-talk, incretin hormones, and the autonomic nervous system, among others. On the other hand, glucagon has manifold effects on glucose, fatty acid, and amino acid metabolism, as well as a significant impact on thermogenesis, satiety, and the cardiovascular system. This article collates the physiological mechanisms of glucagon secretion and action, incorporating the latest in glucagon research.