Glucose tolerance test is a laboratory test used to diagnose diabetes. Glucose tolerance test generally refers to oral glucose tolerance test (OGTT), which is used to understand the function of pancreatic β-cells and the body’s ability to regulate blood glucose, and is a confirmatory test for diagnosing diabetes, as well as an important test for understanding the severity of diabetes. The method of OGTT is to dissolve 75g of anhydrous glucose in 250-300ml of water in the early morning on an empty stomach and drink it in 5-10 minutes, and then draw blood for glucose test before taking glucose, 30 minutes, 60 minutes, 120 minutes and 180 minutes after taking glucose orally. Eating, drinking and strenuous exercise are prohibited during the whole test. The glucose tolerance test should be conducted under the supervision of a doctor.