When monitoring blood glucose, it is not an absolute case that the first drop of blood should not be used. The reason is usually related to the cleanliness of the skin at the test site, the use of disinfectants, and the exudation of inter-tissue fluid. When measuring blood glucose, 75% alcohol is generally used to disinfect the skin at the test site, at which time the first drop of blood will have alcohol in it and the blood will be diluted, causing inaccurate values. If the disinfection is not complete, there will be some impurities or bacteria on the skin surface, and the first drop of blood will have impurities or bacteria, which will also cause the inaccurate value. If the first drop of blood is squeezed hard during the operation, it will cause the blood to contain some tissue fluid, which will have some effect on the value. Blood glucose will change at different monitoring time periods, and is generally divided into fasting blood glucose and postprandial blood glucose. After 8-10 hours of fasting, the normal blood glucose range is 3.9-6.1mmol/L. And the postprandial blood glucose varies according to the time after eating. 2 hours after the meal food is absorbed and transformed by the body, the normal blood glucose is generally <7.8mmol/L. After measuring the blood glucose, the fluctuation of blood glucose is monitored according to the standard of normal blood glucose.