There is no clear stipulation on what time in the morning is better to measure blood glucose, and it is generally believed that it is better to test blood glucose from 6:00 a.m. to 8:00 a.m. in clinical work. Normal fasting blood glucose level generally fluctuates between 3.9~6.1mmol/L, fasting blood glucose testing generally requires fasting time of 8~10 hours, if the morning fasting blood collection time is late, fasting time is too long, which may lead to inaccurate testing of fasting blood glucose level. Therefore, clinically, the blood is usually collected from 6:00 to 8:00 a.m. in the morning on a fasting basis for testing. It is recommended that patients choose the time to measure fasting blood glucose according to their own needs, and if they are not sure, they can consult their doctor and follow the doctor’s instructions to collect blood for fasting blood glucose check on time.