This diagram below shows how insulin and glucagon control blood 
glucosehomeostasis. Insulin and glucagon are the chief hormones that control carbohydrate metabolism. Insulin is a powerful hypoglycaemic agent, whereas glucagon, its counterpart, is a hyperglycaemic agent.
In the liver, glycogen is easily broken down to glucose (glycogenolysis). Glycogen is broken down into pyruvic acid or lactic acid in anaerobic conditions in the muscle tissue, which are then converted to glucose in the liver.
