This paragraph is an abstract of Baidu Encyclopedia, which I think is of great reference significance. The main forms of sugar in human body are glucose and glycogen. Glucose is the transport form of sugar in the blood, which plays a major role in human glucose metabolism. Glycogen is a polymer of glucose, including liver glycogen, muscle glycogen and kidney glycogen, which is the storage form of sugar in the body. Both glucose and glycogen can be oxidized in the body to provide energy. The metabolic pathways of sugar in the body mainly include anaerobic glycolysis of glucose, aerobic oxidation, pentose phosphate pathway, glycogen synthesis and glycogen decomposition, gluconeogenesis and other hexose metabolism.

The following is my answer.

Glucose metabolism is the center of other metabolism because pyruvate and glucosyl -6- phosphate (hereinafter referred to as PA and G-6-P) are the key branching points:

(1)G-6-P can be converted into glucose (bidirectional) or participate in pentose phosphate pathway.

(2)G-6-P and glycogen can be transformed by glycogen synthesis or glycogen degradation.

(3)G-6-P is transformed into PA through glycolytic pathway, and PA can be transformed into G-6-P through gluconeogenesis.

(4)PA is an important substance involved in amino acid cycle, and participates in transamination together with α-ketoglutaric acid and glutamic acid.

(5) (5) Acetyl coenzyme A formed by oxidation of PA is the substrate of citric acid cycle.

(6)PA and lactic acid can be transformed into each other.

In addition, reduced coenzyme (NADH) produced by glycolysis, including reduced coenzyme (NADH, FADH2) produced by citric acid cycle, participates in electron transfer and oxidative phosphorylation to synthesize ATP. This is related to the energy supply of lipid metabolism, amino acid metabolism and nucleotide metabolism.