When should I do prenatal glucose tolerance test?

The glucose tolerance test is a relatively important prenatal test item. Through the glucose tolerance test, we can know the blood sugar level of the pregnant woman. If the pregnant woman is found to have gestational diabetes, the body can be adjusted in time to reduce the impact of gestational diabetes on the fetus. Glucose tolerance tests also require a certain time. Generally, the best time to test glucose tolerance is between the 24th and 28th weeks of pregnancy.

Best time to test glucose tolerance

The best time to do a glucose tolerance test is between 24 and 28 weeks of pregnancy. At present, hospitals in my country generally use the industry standards for the diagnosis of gestational diabetes mellitus set by the Ministry of Health. That is, for expectant mothers with normal fasting blood sugar in early pregnancy, it is generally recommended to undergo a formal 75g glucose tolerance test at 24-28 weeks of pregnancy to monitor blood sugar levels on an empty stomach and 1 and 2 hours after drinking sugar.

Inspection process

Sugar screening test method: Fast for 12 hours before screening, dissolve 50 grams of glucose powder in 200 ml of water, drink it within 5 minutes, start timing from the first sip, draw blood for blood sugar test 1 hour later, blood sugar value ≥7.8mmol means sugar screening is abnormal and further glucose tolerance test (OGTT) is required.

Method of glucose tolerance test (OGTT): Fast for 12 hours before the test, first draw blood for blood sugar on an empty stomach, then add 150ml of 50% glucose injection to 100ml of water, or dissolve 75g of glucose powder in 300ml of water, drink it within 5 minutes, start timing after the first sip, draw blood for blood sugar after 1 hour, 2 hours, and 3 hours. The normal value standard is: 5.6mmol/L fasting, 10.3mmol/L at 1 hour, 8.6mmol/L at 2 hours, and 6.7mmol/L at 3 hours. If 2 or more of these items reach or exceed the normal value, it can be diagnosed as gestational diabetes; if only 1 item is higher than the normal value, it is diagnosed as impaired glucose tolerance. The most important thing is: you must wait more than an hour after drinking the sugar water before drawing blood!

Things to note before glucose tolerance test

1. Three days before the test, the carbohydrate intake (rice, pasta) should not be less than 150 grams. If the subjects deliberately reduce the amount of staple food, the test results will be inaccurate, leading to misdiagnosis.

2. Normal physical activity should be carried out 3 days before the test. However, strenuous exercise before the test can excite the sympathetic nerves and increase blood sugar. Infection, trauma, and drastic mood swings can all excite the sympathetic nerves and affect the results of glucose tolerance tests.

3. When doing the glucose tolerance test, the expectant mother must fast for 8 to 14 hours, which can truly reflect the fasting blood sugar level. For example, if you are doing a glucose tolerance test at 8 o'clock in the morning, it is best not to eat since 10 o'clock the night before. You can drink water, but not tea or coffee.