When should blood glucose monitoring be performed? How often is the right time to test blood glucose in a diabetic patient? For this question, it must depend on the specific condition of each patient. Generally speaking, blood glucose testing can be divided into fasting blood glucose, pre-meal blood glucose, 2-hour post-meal blood glucose, bedtime blood glucose, random blood glucose, etc. according to the time. The blood glucose detected at different times has different clinical significance. 1. Fasting blood glucose: It refers to the blood glucose value measured before breakfast after fasting for more than 8 hours overnight. The blood glucose measured before lunch and dinner cannot be called fasting blood glucose. 2.Pre-meal blood glucose: It refers to the blood glucose value measured before breakfast, lunch and dinner. 3.2 hours postprandial blood glucose: It refers to the blood glucose value measured after breakfast, lunch and 2 hours after dinner. 4. Random blood glucose: It refers to the blood glucose value measured at any other time of the day: such as blood glucose before bedtime, blood glucose at midnight, etc. As for each diabetic patient, the appropriate time and frequency of blood glucose testing should first be discussed with the doctor and should be arranged as reasonably as possible for the condition. Generally speaking, when blood glucose is high recently, fasting and 2-hour postprandial blood glucose should be measured, because fasting and 2-hour postprandial blood glucose can reflect the degree of elevated blood glucose of patients more accurately. When hypoglycemia occurs frequently recently, it is better to test preprandial blood glucose and nighttime blood glucose, because hypoglycemia occurs more often before meals and at night. In addition, it is better to test blood glucose at different times of the day at intervals than to test it at the same time every day. This is because the former is more likely to reflect the pattern of blood glucose changes during the 24 hours of the day, whereas if you take blood glucose at the same time every day, you will never know the level of blood glucose at other times of the day. For patients with stable blood glucose control, the interval between blood glucose tests can be longer, two or three weeks, or even longer. However, for patients with recent large fluctuations in blood glucose, the frequency of testing should be increased according to their condition. For patients with diabetes treated with insulin, newly diagnosed patients with diabetes, patients with frequent hypoglycemia, patients who need to change medication or adjust medication dosage of diabetes, and pregnant patients with diabetes, they should strengthen blood glucose testing and increase the frequency of blood glucose testing. Diabetic patients should also strengthen blood glucose testing when their usual regular life is broken when they are sick, have surgery, or go out, which can easily cause blood glucose fluctuations. Diabetic patients are prone to serious hypoglycemia before and after exercise and after drinking alcohol, so it is also necessary to conduct blood glucose testing at these times. In addition, it is very dangerous to have hypoglycemia while driving, so it can be a good habit to test blood sugar before driving. For diabetic patients who do not have the condition to have blood glucose test at home, they should go to the hospital or outpatient clinic to have fasting and/or postprandial blood glucose test regularly according to the doctor’s suggestion.