In humans the amount of glucose in the blood at any given time is regulated very carefully. If your blood glucose level is too high, your body releases a chemical called insulin into the bloodstream, signaling that it’s time to convert some of the extra glucose floating around into glycogen. Similarly, if your blood glucose level gets too low, your body releases a chemical called glucagon into the bloodstream, telling your body to start breaking down that glycogen to release more glucose into the blood.