Why do I need to be fasting before a physical examination?

Fasting requirements before physical examination are mainly for some items, such as common blood glucose, biochemical tests, B-ultrasound, gastroscopy, etc., the general fasting time requirement is 8-14 hours, patients only need to stop eating after dinner, can meet the fasting requirements. In addition, the best time for patients to draw blood is before 9:30 in the morning.