Final answer:
Dietary glucose is either used immediately for fuel or stored as glycogen or fat. The body can also use alternative sources such as fatty acids and proteins as fuel.
Step-by-step explanation:
During the absorptive state, dietary glucose is absorbed across the intestinal membrane into the bloodstream and used immediately for fuel. Any excess glucose is stored as glycogen in the liver and muscle cells, or converted into fat in adipose tissue.
In the postabsorptive state, when glucose levels drop, the pancreas releases glucagon to stimulate the breakdown of glycogen into glucose. If glycogen stores are depleted, alternative sources such as fatty acids and proteins can be metabolized and used as fuel.