Glucose tolerance test is a laboratory test used to diagnose diabetes mellitus, which requires fasting and taking glucose water and then drawing blood to test blood sugar. Glucose tolerance test is generally referred to as oral glucose tolerance test (OGTT), subjects need to be fasting early in the morning venous blood collection to determine blood glucose, and then dissolve 75g of glucose in 300ml of water, within 5 minutes to drink, in the service of glucose in the 1/2, 1, 2 hours (if necessary, can be 3 hours) each blood glucose measurement. Fasting blood glucose is less than 6.1 mmol/L, blood glucose after oral glucose 30-60min can reach the peak, the peak value is less than 11.1 mmol/L, 2 hours blood glucose is less than 7.8 mmol/L, this is the normal glucose tolerance. Glucose tolerance test should be conducted under the guidance of a doctor, if the blood sugar is abnormal, it is recommended to treat under the guidance of a doctor.