Measurement of fasting blood glucose, which usually refers to early morning fasting blood glucose, usually requires fasting for more than 8 hours. Patients are advised that they should fast and abstain from food and water after 8 p.m. the night before and go to the hospital by 6-8 a.m. the next day, or use a blood glucose meter at home to measure fingertip blood glucose. The night before the fasting blood glucose test, patients should be careful not to drink alcohol, coffee or strong tea and other stimulating drinks. It is because after drinking coffee and strong tea in the evening, sleep disorder will easily occur, leading to poor rest or disorder in the metabolism of the body’s hormone level, which will affect the accuracy of fasting blood glucose values. In addition, the day before the test, the patient’s diet should be the same as usual and should not overeat to avoid affecting the test results. The fasting blood glucose value for normal people is 3.9-6.1mmol/L. In case of pregnant women, the fasting blood glucose should be <5.1mmol/L, and for diabetic patients, the fasting blood glucose should be controlled at 6.5-7.5mmol/L. For older patients, the fasting blood glucose value can be relaxed appropriately, but it is better not to exceed 8.0mmol/L. If the patient has other diseases, such as hypertension, heart disease, etc., they can take medication before the examination, or drink a small amount of water, but be careful not to drink sugar water, drinks, etc. If fasting blood glucose is >6.1mmol/L, patients are advised to recheck their blood glucose. If after the recheck, the fasting blood sugar is 6.1-7.0mmol/L, but the 2-hour postprandial blood sugar is within the normal range, it indicates that the patient has impaired fasting blood sugar and belongs to pre-diabetes, and should be controlled according to the principles of diabetes treatment.