The concept, source and destination of blood glucose

The concept of blood glucose

Glucose in blood is called blood glucose. Its content in blood can be determined by chemical methods. The blood glucose concentration of normal people remains stable, with little change in fasting and postprandial. At present, various hospitals basically use glucose oxidase method or o-toluidine method to determine the glucose content in plasma, also known as true sugar method. Using similar principles, people have invented a simple instrument, called blood glucose meter, It can measure the glucose concentration in whole blood.

Now the legal unit of glucose value is millimolar / liter (mmol/l), but some patients are familiar with the customary unit of milligram% (mg/dl) in the past, which brings inconvenience for patients to determine the blood glucose level by themselves, but it is very simple to remember that the conversion coefficient between the two is 1mmol/l=18 mg/dl.

The concept, source and destination of blood glucose
The concept, source and destination


Blood glucose mainly comes from sugars in food, which are also carbohydrates. Foods with more sugars include Cereals, various sugars, syrups, and various fruits. Sugars can be divided into polysaccharides, disaccharides, and monosaccharides. Starch contained in rice, flour and sweet potato is polysaccharide, which is polymerized by many glucose. Sucrose in brown sugar, white sugar and lactose in milk are disaccharides, which are respectively composed of glucose, fructose and galactose. The sugar in fruit is mainly glucose. Common monosaccharides are glucose, fructose and galactose.

Only monosaccharides can be absorbed into the blood by the human intestine. The most important monosaccharide is glucose, It is the main energy source of all organs. If the human body is a complex machine, blood glucose is the main fuel for the machine to operate.

In fasting, all blood glucose comes from the liver. The liver stores liver glycogen. When needed, liver glycogen decomposes into glucose, which flows into the blood to supplement glucose in the blood, so that blood glucose will not be reduced.

In addition, amino acids absorbed from protein digestion, glycerol from fat and lactic acid generated by muscle can be converted into glucose through gluconeogenesis, which can not only directly supplement the glucose level during starvation, but also further convert into liver glycogen, which can be converted into glucose when needed. Gluconeogenesis is also an important source of glucose.

The destination of blood glucose

Under normal circumstances, the blood glucose level increases after meals, but it remains below a certain level. This is because blood glucose undergoes metabolic transformation through the following five channels with the help of insulin.

  • it enters various organs and tissues of the body, such as brain and heart. It can be used as fuel to generate energy and heat and maintain the life activities of the human body.
  • a small part enters the cells of various tissues and is transformed into components of cells.
  • it enters the liver and becomes hepatic glycogen for storage.
  • enter muscle tissue to become muscle glycogen and store it.
  • enter adipose tissue, transform it into fat and store it.

Hepatic glycogen

Hepatic glycogen is the main storage form of glucose in the body, which is polymerized from a lot of glucose and can be decomposed into glucose. After a meal, glucose absorbed from the intestine enters the blood. It first flows into the liver, 60% – 70% of which is converted into glycogen in the liver for storage. Under normal conditions, the glycogen content in the liver is about 100 g. New glycogen is produced in the liver after each pre meal, but the amount is limited, which is only enough for 5-6 hours. However, even if we are starved for 2-3 days, liver glycogen will not decrease and blood glucose will not decrease.

This is because there is a complex compensatory regulation mechanism in the body. During fasting and starvation, amino acids produced by protein decomposition, glycerol produced by lipolysis and lactic acid produced by muscle contraction can be converted into liver glycogen in the liver. This process is also called gluconeogenesis.

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