When I tested high on my glucose screening test several weeks ago I immediately started looking up information on the glucose tolerance test that I would have to have.  What I found was that there really isn’t a whole lot of information out there about gestational diabetes and the glucose tests that are done to determine if a woman has gestational diabetes.  Gestational diabetes is actually one of the most common pregnancy complications, occurring in about 4% of pregnancies.

Now that I have had and passed my glucose tolerance test (no gestational diabetes for me) I thought I would share some of the information I learned from my experience and what the tests were like for me.  I have found that it is always better to have a little knowledge about what to expect than to go into a test blindly.

As with anything else you should always discuss your concerns, fears, and questions with your doctor.  They know your situation and pregnancy best and can advise you on the specifics for you.

Glucose Screening Test: In a majority of cases your prenatal care provider will send you for a glucose screening test some time toward the end of your second trimester (this is the time when gestational diabetes most often begins).  This may vary depending on your particular situation.  I had my glucose screening test done at 25 weeks.  This test does not require you to fast.  You will go into either your doctor’s office, the hospital, or a lab (I had mine done at Quest Diagnostics).  When you arrive you will be given a 50 gram serving of the glucose drink.  You will be asked to drink this glucose drink and let the phlebotomist know when you have finished at which time a timer will be set for 60 minutes.  You will have to sit around and wait, when 60 minutes has past your blood will be drawn.  I had one small vile of blood taken from my test and from what I understand this is pretty typical.  In my case the lab sent my results to my doctor’s office a few days later.  What is considered a high result on the glucose screening test will depend on what gauge your doctor uses.  Some doctors use 140mg/dl as the cut off while others use 130mg/dl.  If your test results are higher than the cut off you will be sent in for a glucose tolerance test.  The screening tells the doctor that you may be at risk for having gestational diabetes; however, it does not tell your doctor that you do indeed have gestational diabetes.  The screening test, like many other screening tests, results in a lot of false positives, which is why you will be sent in for the more accurate glucose tolerance test for a definitive answer.

Glucose Tolerance Test: This test will be ordered if you test high on the glucose screening or if you have blood in your urine before the screening test was done.  The glucose tolerance test is much more accurate and of course a much longer test.  This test takes 3 hours in most cases and requires you to fast prior to going in for the test.  You will be asked to fast for 8-12 hours prior to the test time (I was told 12 hours but I have seen information indicating that some women are told 8 hours).  When you arrive for the test your blood will be immediately drawn (again about one small vile), this is your fasting test.  You will then be given twice as much of the glucose drink as you were given at the screening test, 100 grams.  Again, you will be asked to drink the glucose drink and a timer will be set when you have finished the drink, this time to go off at 1 hour intervals for the next 3 hours. At each hour your blood will be drawn, for a total of 4 including the fasting test.

Here is what is typically considered abnormal results on the glucose tolerance test (check with your doctor to see what they use)

• Fasting: 95mg/dl or higher
• 1 Hour: 180 mg/dl or higher
• 2 Hour: 155 mg/dl or higher
• 3 Hour: 140 mg/dl or higher

If you have abnormal an result (which is considered high on two or more of the blood draws) on this test then you will be diagnosed with gestational diabetes and your doctor will work out a treatment plan with you.   Gestational diabetes is typically treated primarily with changes in diet and exercise.  If this does not work then other options such as medication or insulin injections will be considered.  You will be required to routinely test your blood sugar throughout the day to help monitor your condition.  Women who have gestational diabetes typically have larger than average babies.   Be sure to discuss any questions or concerns you have with your doctor.

One personal recommendation I can make is that you take a good book or something else to occupy yourself to both the screening test and the glucose tolerance test.  It can seem like you are there a very long time, especially at the glucose tolerance test which is 3 hours or more and you haven’t eaten anything in over 12 hours.

You can read my previous article on gestational diabetes for more information on causes, treatment, and possible complications associated with gestational diabetes.  You can also visit the American Diabetes Association website for more information as well.