Glycogen metabolism, as well. In hypoglycemia caused by excessive insulin, liver glycogen levels are high, but the high insulin levels prevent the glycogenolysis necessary to maintain normal blood sugar levels. Glucagon is a common treatment for this type of hypoglycemia. Various inborn errors of metabolism are caused by deficiencies of enzymes necessary for glycogen synthesis or breakdown. These are collectively referred to as glycogen storage diseases. Long-distance athletes, such as marathon runners, cross-country skiers, and cyclists, often experience glycogen depletion, where almost all of the athlete's glycogen stores are depleted after long periods of exertion without sufficient carbohydrate consumption. This phenomenon
Glycogen-branching enzyme deficiency known as glycogen synthase. This bond may be broken by amylase when the body wishes to break down glycogen into glucose for energy. Glycogen branching enzyme is responsible for the required α-1,6-glycosidic bonds needed to start a branch off of these linear chains. These branches are important, as they provide additional "free ends" for linear chains of α-1,4-glycosidic bonds, which can then be broken down by amylase. This allows for glucose to be removed at a faster rate than if all glucose molecules were in a single chain with only two free ends on which amylase could attach. GBED is