Fasting blood glucose measurements are usually accurate after drinking small amounts of water, but drinking large amounts of water may cause blood dilution and affect the accurate value of fasting blood glucose measurements. Note that if a sugary drink is consumed, it can affect the accuracy of the fasting blood glucose measurement. Fasting in medical terms is defined as fasting for more than 8 hours and not more than 12 hours. If the patient is thirsty before the fasting blood glucose measurement, he/she can drink a small amount of water (e.g. plain water, mineral water, purified water, etc.), which usually will not affect the measurement value. The normal value of fasting blood glucose is between 3.9~6.1 mmol/L. It is recommended that patients with abnormal fasting blood glucose actively cooperate with the doctor, clarify the type of disease under the doctor’s guidance, and carry out standardized treatment, so as to avoid delaying the condition and triggering adverse consequences.