The glucose level in the blood is controlled by several hormones. Hormones are chemicals in the body that send messages from cells to other cells. Insulin is a hormone made by the pancreas. When you eat, the pancreas makes insulin to send a message to other cells in the body. This insulin tells the cells to take up glucose from the blood. The glucose is used by cells for energy. Extra glucose that is not needed right away is stored in some cells as glycogen. When you are not eating, cells break down the stored glycogen into glucose to use as energy.