Here's why:

* Glucose is the most readily available sugar in the bloodstream. It comes from the breakdown of carbohydrates in food and is transported throughout the body.

* Glucose is the preferred fuel source for most cells. It's readily broken down through cellular respiration, a process that produces ATP, the energy currency of the cell.

* Glucose is easily regulated. The body has mechanisms to maintain stable blood glucose levels, ensuring a constant supply of energy for cells.

While other sugars exist in the bloodstream, glucose is the most important one for cellular energy production.