Glucose is a monosaccharide, which can directly supply energy, and it is also the only sugar in the body that can directly supply energy. Moreover, it is a reducing sugar, which can react with weak oxidants, such as Fehling reagent (similar reagents are used to check the sugar in urine in hospitals) and Torrance reagent (silver mirror reaction).

White sugar is sucrose, but it is not pure. Sucrose is binary sugar, which can be obtained from sugarcane (south) and beetroot (north).

Sucrose is a non-reducing disaccharide, which is formed by the contraction of a glucose molecule and a fructose molecule on a specific bond. It cannot react with the above weak oxidant. After being ingested by the human body, glycogen that is decomposed into two molecules of glucose for energy supply or converted into glycogen is stored in the body.