Whether fasting blood glucose can be measured after drinking water needs to be looked at specifically, if you drink less water, then yes. If you drink more water, you can not, need to choose to arrange time to test again. 1. Drinking less water: If the patient drinks plain water and only takes one or two sips, it has little effect on the blood and can be measured after drinking water. 2. Drinking a lot of water: However, if the patient drinks a lot of water, it may dilute the blood and affect the accuracy of the test results, at this time it is not possible to retest, and it is necessary to schedule another time at a later date. To summarize, a small amount of water has little effect on the test results, and a large amount of water has a greater effect, and should be avoided as much as possible, so as not to bring unnecessary trouble. It is also recommended to go to a regular hospital for blood glucose measurement in order to understand the blood glucose situation.