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Pregnancy Glucose Tolerance Tests

Katlyn Joy |25, March 2013


Diabetes that develops during pregnancy is referred to as gestational diabetes and can affect both your and your baby's health. Routine testing with the Glucose Challenge Test and possibly the Glucose Tolerance Test are performed between 26 and 28 weeks of pregnancy. These tests help determine whether your body is processing the sugars you consume properly.

The Glucose Challenge Test

For this test, no special preparations are required of the pregnant women. She will usually have the test done at the doctor's office or at a hospital lab. Once at her appointment she will be given a syrupy sweet drink. An hour after drinking the solution, her blood will be drawn as this will be when peak blood glucose levels will be reached. There is no need to fast prior to this test.

If the levels of glucose are high, then the woman may be at risk for gestational diabetes and further testing will be done. However, a significant amount of women will test positive with the challenge as a false positive as the later testing will reveal.

The Glucose Tolerance Test

For women who tested positive in their glucose challenge test, the next step will be to take the glucose tolerance test. For this test, the pregnant woman will be asked to consume at least 150 milligrams of carbohydrates for a few days prior to testing. This is not a large amount of carbohydrates to eat, however. Also, you will be asked to fast before the test. This means for 14 hours before the test you are to have nothing to eat and nothing but sips of water to drink. For this reason, most women schedule this test for this thing in the morning to avoid feeling lightheaded or ill from lack of food.

The test begins by having blood drawn, in order to obtain a baseline reading of the sugar levels in the blood. Then it's time drink another sugary solution, however this time it's a larger or more concentrated drink. Your blood will be drawn hourly for the next three hours in order to determine how the body is processing sugar.

According to the American Diabetes Association the following levels are abnormally high:

  • Fasting level of 95 mg/dl or higher
  • At one hour - 180 mg/dl or higher
  • At two hours - 155 mg/dl or higher
  • At three hours, 140 mg/dl or higher

If a woman has an elevated reading for one result, she'll most likely retest later after your doctor has instructed you on diet concerns. If she has two or more abnormally high readings, she will be diagnosed with gestational diabetes and be under special care. She will be monitored closely for glucose levels and given nutritional information. She'll also probably be asked to exercise regularly to help keep blood sugar levels in check.

Once she has given birth the doctor will check glucose levels again. Glucose levels will probably be retested at several weeks following birth to make sure the glucose levels have settled back down to a normal amount.

Most women who develop gestational diabetes will not develop diabetes later, but there is a risk so follow up is important. All adults should have their levels checked every few years to make sure they are not falling into the category of pre-diabetes.

This type of diabetes is able to be handled through diet and lifestyle. Eating healthy and staying active are great ways to protect yourself from this disease.

For babies born to mothers with gestational diabetes, the risks include being larger than average birth weight babies, being born prematurely, developing conditions such as low blood sugar or jaundice. If left untreated, gestational diabetes can result in fetal death. It may also contribute to a baby developing diabetes later in life. However, screening makes these risks quite low as once a problem is identified. Pregnant women with gestational diabetes are carefully monitored and if she follows her doctor's instructions, the condition can be safely managed without negative effects.

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