Drinking water to measure blood glucose is generally accurate, but there are some differences in measuring blood glucose indicators at different stages. Normally, the normal value of fasting blood glucose is 3.9-6.1mmol/L, while the normal value of postprandial blood glucose is <7.8mmol/L. Fasting blood glucose refers to the blood glucose value measured after at least 8~10 hours without food, except for drinking water. Therefore, drinking water does not affect blood glucose measurement, generally within the above normal range, are normal phenomena. If the blood glucose measurement after drinking water is out of the normal range, it is recommended to repeat the measurement on a different day for confirmation. If it is still in a higher or lower state, it needs to be taken seriously. Generally speaking, if the fasting blood glucose is higher than 6.1mmol/L or the blood glucose 2 hours after meal is higher than 7.8mmol/L, it can be considered as hyperglycemia, and if it is lower than 2.8mmol/L, it can be considered as hypoglycemia. It is recommended to measure blood glucose correctly under the guidance of a doctor and monitor the changes of your own blood glucose value on a regular basis.