How long should one fast for fasting blood glucose?
Disease description:
I need to measure my fasting blood sugar tomorrow. I would like to ask, how long should the fasting period be? Should it be calculated from the previous night, or does fasting for several hours in the morning of the same day count?
Doctor's answer (1)
Dr. Liu Feng
Fasting blood glucose refers to the blood glucose level measured after an overnight fast of at least 8 hours.
During this period, no caloric food or beverages should be consumed, except for water. This is because after eating, sugars from food are absorbed into the bloodstream, causing blood glucose levels to rise. The fasting state avoids this influence, thereby more accurately reflecting the basal insulin secretion status and hepatic glucose output, which aids in diagnosing diabetes, evaluating pancreatic function, and monitoring treatment effectiveness.
It is recommended to start timing from the end of dinner and maintain a fasting state until blood collection the next morning. For example, if dinner is consumed between 18:00 and 19:00, blood collection can be scheduled between 06:00 and 09:00 the following day, ensuring an interval of at least 8 hours but not exceeding 12 hours.
Fasting for less than 8 hours or longer than 12 hours may affect the accuracy of blood glucose measurements. Therefore, patients preparing for a fasting blood glucose test should strictly control the fasting duration. Standardized fasting duration and preparation measures are key to ensuring accurate fasting blood glucose test results.
