The normal range of fasting blood glucose for normal people is 3.9-6.1mmol/L and 2h postprandial blood glucose＜7.8mmol/L. Drinking a small amount of drinking water in the middle of the night, drinking <200ml, will not dilute the blood and generally will not affect the result of blood glucose testing the next day. However, if you drink sugar water, honey water, drinks, milk with sugar, etc., it may affect the result of blood glucose test. Ordinary drinking water does not contain glucose, so it has no effect of raising blood glucose, but drinking a large amount of water may cause blood dilution and make the measurement value low and affect the accuracy, so try not to drink water in the middle of the night, but drink a little drinking water if you are thirsty. In order to ensure the accuracy of blood glucose measurement the next day, in addition to drinking water, we also need to pay attention to the following points: 1. The requirement of fasting blood glucose is generally fasting > 8h, generally require not to eat any food after 8pm, rest for one night, and test blood glucose around 6-8am the next morning, the blood glucose tested at this time is called fasting blood glucose; 2. For patients with diabetes, the purpose of blood glucose test is to understand the control of blood glucose and observe the effect of medication, so they need to take glucose-lowering medication on time the night before the test; they should stop taking glucose-lowering medication on the day of blood test; 3.