Clinically, fasting blood glucose refers to fasting for more than eight hours. If the fasting time is too long, it will often cause low fasting blood glucose monitoring results, which can lead to reactive hyperglycemia if hypoglycemia occurs. Therefore, it is recommended that patients should pay attention not to fast for too long when performing fasting blood glucose monitoring to avoid affecting the test results. Through fasting blood glucose monitoring in the clinic, patients can understand the control level of basal blood glucose and thus the secretion of basal insulin. In the clinic blood glucose monitoring is recommended into pairs of blood glucose monitoring, such as fasting blood glucose and post-breakfast blood glucose monitoring, in order to understand the situation of blood glucose fluctuation and better guide the clinical treatment. The monitoring of fasting blood glucose must be accurate and avoid prolonged fasting time to avoid the error of monitoring low blood glucose.