Can I drink water on the night before a glucose tolerance test?

It is permissible to drink water the night before a glucose tolerance test, but the following points should be noted:

1. Type of water: Only plain boiled water, which contains no calories, should be consumed. Sugary drinks such as sweetened water or fruit juice should be avoided as they may interfere with the test results.

2. Amount of water: Consumption should not be excessive, as drinking large amounts of water may cause frequent urination during the night, which can disturb sleep and potentially affect blood glucose levels the next day. Generally, it is sufficient to drink a small amount when thirsty.

3. Fasting duration: A sufficient fasting period, usually 8–12 hours, is required before the glucose tolerance test. Therefore, you should stop eating after dinner the previous night, although you may drink a moderate amount of water.

In summary, drinking water is allowed the night before a glucose tolerance test, but only plain boiled water and in limited quantity, to ensure accurate test results. Additionally, the examinee should maintain healthy lifestyle habits and a calm mindset, ensure sufficient fasting time and good quality sleep. If you have any concerns, it is recommended to consult a healthcare professional or testing facility.