Updated: 2018, Aug 9

Glucose Screening and Tolerance Test For Safe Pregnancy: Why It Is Important?

By - Reviewed by CHD Team
Glucose Screening and Tolerance Test For Safe Pregnancy

Glucose screening and tolerance tests are routine blood tests recommended to expectant mothers between the 24th and 28th week of pregnancy to determine whether or not they have gestational diabetes. Characterized by poor control in blood sugar during pregnancy, gestational diabetes rarely develops clinical manifestations, and so the screening and tolerance tests are good ways to find out if a pregnant woman has it or not.

glucose screening test first

Generally, pregnant mothers take the glucose screening test first. It should be cleared that the test is not used to diagnose if a pregnant mother has gestational diabetes or not. What the test does is to identify pregnant women who are predisposed to develop gestational diabetes. Once a pregnant woman yields a positive result, a glucose tolerance test is performed. The glucose tolerance test, on the other hand, is a test that is longer and more definitive than the screening test. This is the definitive test for gestational diabetes.

During the glucose screening test, a pregnant woman will be given a sugar solution containing 50 grams of sugar. The solution tastes like a sweet soda that must be taken within 5 minutes. After an hour, a blood sample will be taken from a woman’s arm to check her blood glucose levels. This is done to see how quickly or efficiently sugar is broken down in one’s system. A screening test result that is too high subjects to three glucose tolerance tests that would confirm gestational diabetes. When a glucose tolerance test yields:

  • One Abnormal Reading: Another test may be scheduled within the pregnancy, or the pregnant woman may be instructed to make diet and exercise modifications.
  • Two or More Abnormal Readings: The pregnant woman has gestational diabetes and is subjected to the treatment plan.
Glucose Tolerance Test

According to the American Diabetes Association a Glucose tolerance test is considered abnormal when:

  • It is at 95 mg/dl or higher when fasting.
  • It is 180 mg/dl or higher an hour later.
  • It is 155 mg/dl or higher 2 hours later.
  • It is 140 mg/dl or higher 3 hours later.

Gestational Diabetes: What Is This Condition?

Gestational diabetes is a condition that occurs among pregnant women who develop high levels of blood sugar during their pregnancy. According to studies, roughly 2 to 5 percent of pregnant women develop this condition. As a result, this condition becomes one of the most prevalent and common health problems face by pregnant women.

Gestational diabetes only develops during pregnancy and resolves after childbirth, unless, a pregnant woman had already been diagnosed as diabetic even prior to her pregnancy. However, there are also some cases when women still have high blood glucose levels even after childbirth. Thus, as a routine, women are instructed to take glucose tests 6 to 8 weeks postpartum to make sure that their gestational diabetes did not develop into diabetes.

Gestational Diabetes Test

Most often, gestational diabetes affects women in their late pregnancies. Because of this, the effects of gestational diabetes on the baby or fetus are lesser compared to those who were conceived from diabetic mothers. Unlike babies of diabetic mothers, gestational diabetes babies are spared from the risk of developing birth defects to which babies of diabetic mothers are predisposed to. However, it is still necessary to treat and manage gestational diabetes because it can still hurt the growing fetus in such a way that it makes the fetus’ pancreas work harder to get rid of the extra glucose. This is because maternal glucose crosses the placenta, but the insulin does not. Moreover, since the fetus gets more energy than it needs, the extra energy is stored as baby fats, which will eventually lead to a condition called “macrosomia”. As a result, babies born with macrosomia tend to become big enough, which can be a problem when it’s time for delivery. These babies may have damaged shoulders during childbirth because, because they are too big to pass through the birth canal. These babies are also expected to have extremely low blood glucose levels at birth because their pancreas got used to the excessive glucose levels, while intrapartum. Thus, to prevent these occurrences, it is important for a mother to manage gestational diabetes.

Everything You Need To Know About Glucose Tolerance Test

What Are Expected Occurrences During The Test?

There are pregnant women who may feel nauseated after drinking the glucose solution. There are even those who may throw-up. To prevent these from happening, a pregnant woman must eat something before the screening test. In the event that a pregnant woman vomits after taking the glucose solution, she will be asked to come back on another day for a repeat test. However, it would be more likely for women to feel sick during the glucose tolerance test because the solution to be taken and the consistency is twice as much as that of the screening test.

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