The hormones insulin and glucagon are responsible for the regulation of the level of blood sugar. Alpha cells in the islets of the pancreas produce the hormone glucagon and the beta cells produce the hormone insulin. When the level of glucose is high in the blood, the hormone insulin is released which increases the glucose uptake and metabolism by the cells. When the level of blood sugar is low, the hormone glucagon is released which causes breakdown of glycogen and formation of glucose molecules. The uptake of glucose by the cells is decreased by the action of this hormone.