Diabetes mellitus is a chronic endocrine metabolic disease. The continuous damage of long-term hyperglycemia to human tissue cells will lead to complications in various systems of the body and seriously affect the quality of life and life expectancy of patients, and this process of chronic damage of hyperglycemia to human body is often not felt by patients for many years after the onset of the disease, and is not easily detected at an early stage. Many patients do not actively treat diabetes or do not standardize treatment, and many patients only pay attention to monitoring fasting blood glucose, but ignore the monitoring and control of postprandial blood glucose, which eventually leads to the occurrence and development of various chronic complications, and once these chronic complications occur, treatment not only requires a lot of economic costs, and the efficacy of treatment is not good, and will continue to aggravate, but by then it is too late to regret. Modern diabetes treatment concept is: early diagnosis, comprehensive safety standards, that is, not only to achieve the blood sugar standard, and to avoid hypoglycemia, but also to control blood pressure, blood lipids, weight, etc.. In terms of blood glucose control, it emphasizes balanced control of fasting and postprandial blood glucose. The blood sugar of normal people, no matter fasting or postprandial, is in a relatively stable state (glucose homeostasis), that is, fasting 3.9-6.1 mmol/L postprandial <7.8 mmol/L. In diabetic patients, due to the defect of their own insulin function, the level of insulin secretion decreases, or the ability of tissues to use glucose decreases and other factors, resulting in the increase of fasting or postprandial blood sugar, but in pre-diabetes or However, in pre-diabetes or early diabetes, many patients do not have high fasting glucose but only show postprandial hyperglycemia, i.e. glucose more than 7.8 mmol/L 1-2 hours after meal, while once fasting glucose is elevated (>6.1 mmol/L), basal insulin secretion, which represents pancreatic function, is significantly attenuated and postprandial glucose is often higher, and hyperglycemia has a cumulative effect on the chronic damage to various tissues and cells throughout the body. Studies have proven that fasting hyperglycemia (>6.1 mmol/L) and postprandial hyperglycemia (>7.8 mmol/L) differ in their outcomes leading to chronic complications, with the former correlating with microvascular lesions (mainly including diabetic retinopathy, diabetic nephropathy, etc.) proven by evidence-based medicine, while postprandial hyperglycemia is more associated with macrovascular complications (mainly including cardiovascular and cerebrovascular lesions such as At the same time, blood sugar fluctuation (i.e. variation or amplitude of fasting and postprandial blood sugar) is considered as an independent risk factor of vascular damage, therefore, the blood sugar control of diabetic patients should monitor or control both fasting blood sugar and postprandial blood sugar (including the blood sugar after three meals), and also reduce the variation of fasting and postprandial blood sugar, i.e. smoothly control fasting and postprandial blood sugar to keep blood glucose stable.