Welcome‎ > ‎Obstetrics‎ > ‎Lab Tests in Pregnancy‎ > ‎

3 Hour Glucose Tolerance Test

3 Hour Glucose Test

            The 3 hour glucose tolerance test (3 hr GTT) is ordered when a pregnant woman has an elevated 1 hour glucose test (above 140).  The 3 hour is different because it will check how the body processes sugar over a longer period of time.

Preparing for the Test

    ·         Call the lab to schedule your test time.          

    ·         Prior to the 3 hour GTT, you should fast for 8 hours.  This means nothing to eat or drink other than some water.  

The Day of the Test

    ·         When you arrive at the lab, they will draw you blood to check a fasting blood level. 

    ·         Then you will drink a solution containing 100gm of glucose.  You cannot eat or drink anything for the next 3 hours.

    ·         The lab will draw your blood again at 1 hour, 2 hours and 3 hours after drinking the glucose.

What do the results mean?

    ·         If all the 4 level of glucose are within normal limits, you do not have gestational diabetes.

    ·         If 1 level is elevated, you have glucose intolerance and need to manage your diet closely.  You should avoid refined sugars like candy, cakes, cookies, or other sweets and change to the whole grain version of carbohydrates like breads and pasta.

    ·         If more than 1 level is elevated, you have gestational diabetes.  You will need to begin monitoring your blood sugar with a meter at home 4 times a day: fasting and 2 hours after breakfast, lunch and dinner each.  You will also need to change your diet by removing refined sugars and white carbohydrates..  If your blood sugars are frequently elevated, you may need to start medication to control your gestational diabetes.