Any method of checking blood glucose is subject to error, but it is relatively more accurate to take venous blood for blood glucose, usually fasting blood glucose and 2 hours postprandial blood glucose (from the first bite of food). There are two common ways to measure blood glucose, one is to take fingertip blood and the other is to take venous blood. When taking fingertip blood for blood glucose measurement, the blood glucose value will be affected by many factors such as sterilization, the degree of blood squeezing, the sensitivity of test strips, the precision of blood glucose meters, etc., and the error may be relatively large; while when taking venous blood for blood glucose measurement, the blood specimen needs to be centrifuged first to remove the white blood cells and other cellular components, and then test the plasma blood glucose level, which will also be affected by the precision of the instrument. Therefore, compared with the fingertip blood glucose measurement, the venous blood glucose measurement is more accurate. Fasting blood glucose and 2-hour postprandial blood glucose (timed from the first bite of food) are generally used as clinical indicators for blood glucose assessment. It is advisable to consult your doctor for details on how to measure your blood glucose.