Glucose screening and tolerance tests during pregnancy

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A glucose screening test is a routine test that is done between 24 to 28 weeks of pregnancy for gestational diabetes. This test checks  a pregnant woman’s blood sugar level. Glucose screening test does not diagnose gestational diabetes. It only identifies a pregnant woman’s possibility of having this problem.


You will be given a liquid that contains  50 grams of glucose to drink. This liquid tastes very sweet and you need to drink all within five minutes. Your blood is drawn an hour later. This test checks how efficiently your body processes sugar.

If your blood sugar is too high, you will need to go back for  a three-hour glucose tolerance test. You don’t need to eat or drink anything for 8 – 14 hours before your test. You can only take small sips of water.  You cannot eat anything during the test.You will be given the liquid containing glucose to drink. Your blood will be drawn every 30 – 60 minutes to check for your blood sugar. This test takes at least 3 hours.


A normal result is a blood sugar that is equal to or less than 140mg/dL 1 hour after drinking the glucose solution. If your  blood glucose is higher than 140 mg/dL, it means the results are abnormal and you will need to go back for an oral glucose tolerance test. You should note that most women whose glucose screening test shows elevated blood sugar don’t turn out to have gestational diabetes.


An abnormal result for three-hour glucose tolerance test is as follows

  • Fasting: greater than 95 mg/dL
  • 1 hour: greater than 180 mg/dL
  • 2 hour: greater than 155 mg/dL
  • 3 hour: greater than 140 mg/dL

If only one of your result is higher than normal, your doctor will suggest diet changes. If more than one result is higher than normal, you have gestational diabetes.


This test is usually done between 24 and 28 weeks of pregnancy. The test may be done earlier if you are at risk of diabetes or you’ve had  high glucose levels in your urine during your routine prenatal visits. Women who have a low risk of getting diabetes may not have the test. To be considered low risk for diabetes, all the following statements must be true

  • younger than 25 years old and have a normal weight
  • your ethnic group has a low risk of diabetes
  • you have never had a test that showed your blood glucose was higher than normal.
  • you have not had any problems with earlier pregnancy
  • you do  not have any first-degree relatives (parent, sibling, or child) with diabetes

Diabetes. Are you at risk ?


There are no special preparations for this test. It is best to take it in the morning because you cannot eat or drink anything8 to  14 hours before the test. You can only have  sips of water. Some people feel nauseated , light-headed or sick after the test. Serious side effects of glucose screening test are very rare.

If you have gestational diabetes , you will work with your practitioner or a diabetes specialist and a nutritionist. Your high blood sugar level only last during the pregnancy. Some women  however still have diabetes after delivery

Glucose screening and glucose tolerance tests. BabyCenter. Access January 8, 2014

Glucose tolerance test. American Pregnancy Association. Access January 8, 2014

Glucose Screening and Glucose Tolerance Testing. Parents. Access January 8, 2014

Glucose screening and tolerance tests during pregnancy. National Library of Medicine. MedlinePlus. Access January 8, 2014

The American Heritage® Stedman’s Medical Dictionary. Retrieved January 2014 from website.

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