Blood glucose 3 hours after a meal belongs to random blood glucose, and the normal range is less than 11.1mmol/L. However, generally blood glucose 3 hours after a meal will drop to the level of fasting blood glucose, which is about 3.9-6.1mmol/L. The normal range of blood glucose includes fasting blood glucose at 3.9-6.1 mmol/L; 2-hour postprandial blood glucose less than 7.8 mmol/L; random blood glucose is blood glucose at any time before, during, or after a meal, and the normal value is less than 11.1 mmol/L. Blood glucose after meal is generally higher than fasting blood glucose. If the blood glucose 2 hours after meal is more than 7.8mmol/L and less than 11.1mmol/L, while the fasting blood glucose is less than 6.1mmol/L, it is considered that the glucose tolerance is abnormal and belongs to prediabetes. Three hours after the meal, the body’s insulin play a role, blood sugar gradually decline, down to the level of fasting blood glucose, if this time the blood sugar is higher than 11.1mmol / L, it is possible to diagnose diabetes. If you find abnormal blood glucose, it is recommended that you go to the hospital in time to get a clear diagnosis and treatment under the guidance of your doctor.