1. It reflects the reserve function of pancreatic B-cells, that is, the ability of B-cells to secrete insulin after the stimulation of food to pancreatic B-cells after meal. If the reserve is good, the surrounding tissues are sensitive to insulin action and there is no insulin resistance, the blood glucose value should drop to a level close to the fasting level 2 hours after meal, generally less than 7.8 mmol/L (140 mg/d1). However, if the reserve function is good, and even some diabetic patients secrete insulin at a level higher than normal, but due to the surrounding tissue resistance to insulin, or resistance is not obvious, but the function of pancreatic islet B cells has been poor, then the 2 hours postprandial blood glucose can be significantly higher. 2, 2 hours after meal blood glucose if more than 11.1mmol/L (200mg/d1), is prone to diabetic eye, kidney, neurological and other chronic complications, for older diabetic patients or complications are still available, but for middle-aged and less serious, because of mild hyperglycemia has a negative impact on blood pressure, cardiovascular, as far as possible to control the postprandial blood glucose at 7.8mmol/L ( 140mg/d1) or less, which is also helpful to reduce the load of pancreatic B-cells and protect the function of B-cells. 3. Monitoring the blood glucose 2 hours after meal can detect possible postprandial hyperglycemia. Many type 1 diabetic patients have low fasting glucose but high postprandial glucose, so if they only check fasting glucose, diabetic patients will often think that their glucose is well controlled and miss the disease. 4. 2 hours postprandial blood glucose can better reflect whether eating and using hypoglycemic drugs are appropriate, which cannot be reflected by fasting blood glucose. 5.Monitoring 2 hours after meal blood sugar neither affects normal medication or injection, nor normal eating, so it does not cause special fluctuations in blood sugar.