Postprandial blood glucose is usually the 2h postprandial blood glucose value, and fasting blood glucose is the blood glucose value taken before breakfast after 8-10 hours of overnight fasting. Postprandial 2h blood glucose and fasting blood glucose are equally important, and failure of either one to meet the standard indicates a problem with the patient’s blood glucose, resulting in abnormal glycated proteins and complications. In normal people, fasting blood glucose is 3.9-6.1 mmol/L and 2h postprandial blood glucose is less than 7.8 mmol/L. The normal range is 4.4-7.8 mmol/L. If fasting blood glucose is ≥7.0 mmol/L and the patient has unexplained weight loss, diabetes is diagnosed. Diabetes is diagnosed if fasting blood glucose is ≥7.0mmol/L and 2h postprandial blood glucose is ≥11.1mmol/L. If the fasting blood glucose is higher than normal and does not meet the diagnostic criteria for diabetes, it is called impaired fasting blood glucose. Postprandial 2h blood glucose is called abnormal glucose tolerance if it is higher than normal and does not meet the diagnostic criteria for diabetes mellitus. Both fasting blood glucose and postprandial blood glucose should preferably be tested once a year, mainly for patients over 40 years old with a family history of diabetes, or patients with a combination of hypertension, hyperuricemia, coronary heart disease, hyperlipidemia, and obesity, which are all causative factors for diabetes to occur. In the case of normal fasting blood glucose, it cannot be judged that the 2h postprandial blood glucose is also normal, and the first symptom of many diabetic patients is elevated postprandial blood glucose as the main clinical manifestation. In the process of physical examination, high-risk people should have both fasting blood glucose and postprandial 2h blood glucose, so that abnormalities in glucose metabolism can be detected earlier and diabetes can be detected as early as possible. Once discovered, diabetes is a lifelong disease that can only be controlled but not cured. The earlier the intervention of diabetes, the better the blood sugar control, which is beneficial to diabetic patients. Well-controlled blood glucose is less likely to produce acute complications and also delays the occurrence and development of chronic complications, which is important for improving the quality of life of patients.