Pre-meal blood glucose generally refers to fasting blood glucose and post-meal blood glucose generally refers to blood glucose 2 hours after a meal. Normal people’s fasting blood glucose is 3.9-6.1mmol/L, and blood glucose 2 hours after a meal is less than 7.8mmol/L. Fasting blood glucose is a common indicator used to help diagnose disorders of glucose metabolism, and is defined as a blood glucose value that has not been eaten any food for at least 8 hours. For a normal adult, the reference value for fasting blood glucose is 3.9-6.1 mmol/L. The fasting blood glucose is usually measured between half an hour and one hour after eating. Generally, half an hour to one hour after eating, postprandial blood glucose reaches its peak, but it should not exceed 11.1mmol/L. Blood glucose will drop 2 hours after meal, and the normal value should be less than 7.8 mmol/L. If abnormal blood glucose is detected, it is recommended to consult a doctor in time and follow the doctor’s instructions for examination and treatment.