Christian de Duve glucagon was the major hormone influencing the breakdown of glycogen (glycogenolysis) in the liver, by which more sugars are produced in the blood. De Duve's original hypothesis that glucagon was produced by pancreatic alpha cells was proved right when it was demonstrated that selectively cobalt-damage alpha cells stopped producing glucagon in guinea pigs, and finally isolated the purified hormone in 1953, including those from birds. De Duve was the first to hypothesise that production of insulin to decrease blood sugar level stimulated the uptake of glucose in the liver, and that there is a balanced production of insulin and glucagon
Glucose of consumed food. Organisms use glucose as a precursor for the synthesis of several important substances. Starch, cellulose, and glycogen ("animal starch") are common glucose polymers (polysaccharides). Some of these polymers (starch or glycogen) serve as energy stores, while others (cellulose and chitin, which is made from a derivative of glucose) have structural roles. Oligosaccharides of glucose combined with other sugars serve as important energy stores. These include lactose, the predominant sugar in milk, which is a glucose-galactose disaccharide, and sucrose, another disaccharide which is composed of glucose and fructose. Glucose is also added onto certain proteins and lipids in