Your body needs the sugar glucose to provide energy so that your cells and organs can function normally. Glucose is stored in your muscles and liver as a substance called glycogen. Glycogen is essentially made up of a number of glucose units (molecules) joined together. Various different proteins, known as enzymes, help to convert glucose into glycogen for energy storage. Other enzymes break down the glycogen back into glucose when more glucose is needed for energy.
This is a companion discussion topic for the original article at https://patient.info/childrens-health/glycogen-storage-disorders-leaflet