Glycogen is the common form for storing glucose in animal cells, while starch is the common form for storing glucose in plant cells. These saccharides are very similar, but glycogen is more easily digestable due to its structure. Liver and muscle cells are the primary storage places for glycogen. Adipose cells are primarily known for the storage of fats.

When blood glucose levels are elevated, the liver will convert available carbohydrates into glucose, and then convert the glucose into glycogen. This allows for glucose to be stored in the liver until blood glucose levels drop, and it needs to be released. The act of converting glucose to glycogen in the liver is called glycogenesis. Glycogenolysis is the opposite reaction, in which glycogen is converted to glucose once again.

Glycolysis is a step in cell metabolism in which glucose is cleaved into pyruvate. Gluconeogenesis is the production of glucose from non-carbohydrate molecules when glycogen is unavailable.