Normal index value of blood glucose: fasting venous plasma blood glucose is between 3.9-6.1mmol/L, and two hours after meal venous plasma blood glucose is less than 7.8mmol/L, which is called normal, and endocrinology generally takes fasting blood glucose as 5.6mmol/L as the cutting point. Using fasting is best to take blood at 6-8 o’clock in the early morning, do not take hypoglycemic drugs before taking blood, do not exercise, do not eat breakfast, if fasting is drawn too late, the measured blood glucose value will be difficult to reflect the patient’s treatment effect, two hours after meal refers to OGTT two hours to drink glucose 75g taken intravenous blood glucose, the method used is glucose oxidase coupling colorimetric method.