During pregnancy you will have a number of tests that are part of your prenatal care.  One of these tests will be the Glucose challenge screening.  This is done usually between 26-28 weeks of pregnancy.  Your doctor may want to test you earlier if you have diabetes prior to pregnancy, if there is sugar in your pee during an office visit, family history of gestational diabetes, if you are obese, if your blood pressure is high, if you are over 35 weeks, if you have had babies with a high birth weight, or if you have a conditions like polycystic ovarian syndrome

If you fail the glucose challenge screening your doctor will have you do a second test, which is the glucose tolerance test.  The glucose challenge screening and the glucose tolerance test check the levels of blood glucose.  If you have a blood glucose level over 130 mg/dL during the glucose challenge test, it is considered failed.  Then you will move on to having a glucose tolerance test.  This test is longer.  Instead of being a one hour blood draw, it is over the course of three hours.  

The glucose tolerance test identifies abnormalities in the way your body handles glucose after a meal.  It also is the only way for your doctor to diagnose you with gestational diabetes.  


What To Expect At A 3 Hour Glucose Tolerance Test

During the three hour glucose tolerance test you will be asked to not eat 8-10 hours before your test.  Usually tests are scheduled for in the morning so you won’t have to go too long without food.  Water is ok to drink during your fasting period.  When you first arrive at the doctor’s office you will first get a fasting blood glucose level.  After the initial blood draw you will drink a sugary beverage.  This drink consists of more ounces of sugar in the 100 mL drink than the one hour glucose challenge screening.  After drinking the drink within 5 minutes you will have blood draws at the one hour, two hour, and three hour intervals.  You will not be able to eat anything until after the last blood draw.  You are usually allowed to take sips of water during the test.  You will have to remain waiting in the waiting room the whole time.  Bringing something to help occupy yourself can help make the time of the test go faster.  You may have some minor side effects such as nausea or dizziness, but major side effects are rare.  If you feel like you are going to be sick tell someone who is administering you the test, because if you do vomit, the test will be discontinued and you will have to try again.  



You will have four different results.  The first one from your fasting blood glucose level.  An abnormal result for fasting is a blood glucose level of 95 mg/dL or higher.  The one hour blood draw result is abnormal with a level of 180 mg/dL or higher.  The two hour blood draw is abnormal if the level is 155 mg/dL or higher.  The third hour blood draw result is abnormal with a level of 140 mg/dL or higher.  You will usually get your results within one to two days of testing.  If one level comes back abnormal your doctor will change a few things in your diet, then have you come back later in pregnancy and retest.  If you have 2 or more abnormal levels results you will be diagnosed with gestational diabetes.  



Treatment for gestational diabetes can sometimes just come down to changes in your diet and exercise.  Watching what you eat and making sure you get some exercise daily is sometimes all that is needed to keep your blood sugar levels in check.  In some cases your doctor may give you a glucose meter.  This is a machine that checks blood glucose levels with a drop of blood.  Your doctor may want you to monitor your levels in the morning, and after every meal to make sure your levels are normalizing regularly.  If your levels are still not being managed you may need insulin injections.  

Like any medical test you can refuse to take the glucose tolerance test.  Your doctor cannot make you.  This test has become routine for most prenatal care facilities.  Gestational diabetes that goes left unmanaged can cause problems for both the baby and the mother.  Complications of gestational diabetes are preeclampsia, delivering a large baby, your baby having low blood sugar at birth, or the baby being at a higher risk of developing type 2 diabetes.  



The glucose challenge screening is the first step to checking if your body has any abnormalities in the way your body handles glucose after a meal.  If you fail this test, the next step to rule out gestational diabetes is the glucose tolerance test.  It takes about 3 hours, with 4 different blood draws.  Besides some mild symptoms of dizziness and nausea there are not any negative side effects that can come from this test besides the number of needle pricks you will have to endure.  Managing gestational diabetes can lessen the complications in birth for both mother and baby.  These tests are normal standard of care in most prenatal practices.  



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