Which compound is the main sugar transported in human blood?

Glucose is the main sugar transported in human blood.

Glucose is a simple sugar, or monosaccharide, with the molecular formula C₆H₁₂O₆. Cells use it as a major energy source, especially the brain and red blood cells. Blood glucose comes from digested carbohydrates and can also be released by the liver from stored glycogen.

The hormone insulin helps many cells take up glucose from the blood, while glucagon helps raise blood glucose when it falls. The body keeps blood glucose within a regulated range because both excessive and insufficient levels can be harmful.

Glucose is often confused with fructose because they share the same molecular formula, but their structures differ. Sucrose, common table sugar, is a disaccharide made from glucose and fructose. Lactose, the sugar in milk, contains glucose and galactose.