Glucose tolerance generally refers to glucose tolerance test, and there is no optimal time for glucose tolerance test, which is usually available to pregnant women at 24-28 weeks of pregnancy, in the morning at 7-9 am. Glucose tolerance test usually takes 3 or 5 blood tests, it is the first blood collection when fasting after taking a quantitative amount of glucose orally, then the first sip of sugar water starts timing, and then the blood is drawn once in 30 minutes, 1 hour, 2 hours, and 3 hours respectively. Thus, the glucose metabolism function is tested to understand the function of pancreatic β-cells and the body’s ability to regulate blood glucose, which is one of the indicators for the diagnosis of diabetes mellitus. Glucose tolerance test for women during pregnancy can detect whether they have gestational diabetes. Generally pregnant women can be carried out at 24~28 weeks of pregnancy, 7~9 o’clock in the morning. It is mainly detected by taking blood from a vein, and diabetes can be diagnosed when the fasting blood glucose reaches or exceeds 5.1mmol/L or the blood glucose value reaches or exceeds 10.0mmol/L one hour after oral glucose intake or the blood glucose value reaches or exceeds 8.5mmol/L two hours after oral glucose intake. If the result of glucose tolerance test is abnormal, you need to go to the regular hospital in time and take relevant treatment measures.