High blood glucose three hours and four hours after meal can be caused by physiological and pathological reasons, physiological reasons such as eating too many sweets, etc. Pathological reasons may be caused by impaired glucose tolerance or diabetes mellitus, which requires further examination to confirm the diagnosis. Clinically, fasting blood glucose and 2-hour postprandial blood glucose are often used as assessment indicators. Physiological causes: Under normal circumstances, the blood glucose three to four hours after meals is close to the fasting blood glucose. If the blood glucose is high, it may be related to diet, such as eating too many sweets, drinking carbonated beverages, eating too much greasy food, etc., and the postprandial glucose can be rechecked. Pathological causes: such as diabetes mellitus, impaired glucose tolerance, etc. Further tests are recommended to confirm the diagnosis, such as fasting blood glucose, glucose tolerance test, glycated hemoglobin, etc. Consult your doctor for the results.