Glucose tolerance is the abbreviation of oral glucose tolerance test, which is the gold standard for the diagnosis of diabetes and is also used for the diagnosis of gestational diabetes. The oral glucose tolerance test is performed by taking 75g of glucose orally after drawing blood on an empty stomach, timing from the first sip of sugar water, and measuring blood glucose by drawing venous blood 2 hours and 2 hours after taking the sugar, respectively. The normal value of fasting blood glucose is between 3.8-6.0mmol/L. When fasting blood glucose is between 6.0-7.0mmol/L, fasting blood glucose is too high. When fasting blood glucose is greater than 7.0mmol/L, diabetes can be diagnosed if accompanied by the typical symptoms of diabetes. If there are no typical symptoms of diabetes, it needs to be reviewed and confirmed at another different time. The normal value of blood glucose 2 hours after taking sugar is less than 7.8mmol/L. When the blood glucose 2 hours after taking sugar is between 7.8-11.1mmol/L, it is abnormal glucose tolerance. When the 2-hour postprandial glucose is greater than 11.1mmol/L, diabetes can be diagnosed if it is accompanied by the typical symptoms of diabetes. If it is not accompanied by typical symptoms of diabetes, it needs to be reviewed and confirmed at another different time. In the case of oral glucose tolerance test during pregnancy, fasting less than 5.1mmol/L, 1 hour after taking sugar less than 10.0mmol/L, 2 hours after taking sugar less than 8.5mmol/L, any 1 of the above 3 points exceeding the normal value can be diagnosed as gestational diabetes.