The highest point of blood glucose value appearing after meal is usually around 0.5-1 hour after meal. According to the different kinds of food in each meal, the peak value of blood glucose will change accordingly, and usually around 1.5-2 hours after meal, the blood glucose level starts to decline gradually, the above time point is not taken as the time point of monitoring blood glucose for diabetic patients. The diagnosis standard of diabetes is fasting blood sugar and 2 hours after meal blood sugar as the diagnosis standard, usually you can monitor the blood sugar before three meals, 2 hours after three meals and before going to bed. If you want to test the body’s insulin reserve function, you can do a glucose tolerance test by drinking 75g of glucose and testing the blood sugar for 0.5 hours, 1 hour, 2 hours and 3 hours from the first sip, and judge whether the patient’s blood sugar metabolism is normal according to the curve that appears at each point. In normal people, fasting blood glucose is 3.9-6.1 mmol/L and 2 hours after meal blood glucose is <7.8 mmol/L. If fasting blood glucose is ≥7.0 mmol/L and 2 hours after meal blood glucose is ≥11.1 mmol/L then diabetes can be diagnosed. For women in pregnancy, gestational diabetes is diagnosed if fasting blood glucose ≥ 5.1 mmol/L, 1 hour postprandial blood glucose ≥ 10.0 mmol/L, and 2 hours postprandial blood glucose ≥ 8.5 mmol/L. If the patient has only 1 elevated fasting glucose, but has recent unexplained weight loss, the possibility of diabetes also needs to be considered. A doctor should be consulted to confirm the diagnosis in combination with urine glucose, urine ketone bodies, glycosylated hemoglobin and other laboratory results. It is better for diabetic patients to monitor blood glucose according to fasting blood glucose and blood glucose 2 hours after meal, and not to monitor arbitrarily, which has no guiding meaning for the treatment of the disease.