There are two tests for gestational diabetes.  Typically only the first one is needed to screen for diabetes, but if the first test results come back as “failed” then a 2nd test is done (called 3 hour glucose tolerance test) to get a more accurate reading.

Many women can fail the first 1 hour glucose test and take the 3 hour glucose tolerance test to pass with flying colors. If you are already on the 2nd test (3 hour glucose tolerance test) then you must be nervous about the results. So, what happens if you do not pass the 2nd time around?

What to Expect for the First Glucose Tolerance Test

One hour before your blood is drawn for the first test, you will need to drink a sweet 6 to 8 ounce liquid containing 50 grams of glucose.  The glucose drink tastes like a very sweet soda pop that may cause you to feel nauseous but must be drunk within five minutes.  The results from this test will indicate if you are producing enough insulin to handle the glucose solution.  If the reading shows your blood sugar levels are too high, you are required to come back for 3 hour test to get a more accurate reading.  About 15 to 23 percent of the time, this can happen.  Most women who take the 2nd glucose test, pass..
Solution Makes You Sick and Nauseous

Some pregnant women will feel nauseated after drinking the glucose solution and will even throw up.  If you vomit soon after you’ve drank the solution, you will have to come back another day to repeat the test.  Most women are able to hold down the solution fine and it’s actually more common for women to feel sick during the 3 hour tolerance test.  The solution for the 3 hour glucose test may be more sweet or you may have to drink more liquid after a period of fasting.

Abnormal Blood Glucose Level

Each doctor has their own standards on determining whether your glucose level is too high.

Some doctors will say if your one-hour blood sugar level is 140 milligrams of glucose per deciliter of blood plasma (mg/dL) or more, you will need to take the 3 hour glucose tolerance test.  There are other doctors who have a cut off point of 130 mg/dL to catch more women who might be at risk of having gestational diabetes, but increases the chances of more false positives.

If your blood glucose level is higher than 200 mg/dL, most doctors will consider that you are diabetic and will not need you to take the 3 hour glucose tolerance test.

What to Expect for Glucose Tolerance (3 Hour) Test

You will need to fast the night before.  It’s best to schedule the test for first thing in the morning.  Upon arrival, the lab technician will take a fasting blood sample and then ask you to drink a concentrated sugar solution.  For every hour, you will be tested by the lab technician who will withdraw blood and collect a urine sample.  The lab technician should alternate arms when withdrawing blood each time.

You will need to stay in the waiting room between the blood drawings so be ready by bringing reading material and something to eat after the last blood sample is taken.

If one of the glucose readings is abnormal, you may need to take another test later in your pregnancy or your doctor may make some changes to you diet and exercise regimen.  If 2 or more readings are abnormal, you will need to talk with your doctor about a treatment plan.  The following shows the glucose levels that the American Diabetes Association considers abnormal.

Fasting = 95mg/dl or higher

One Hour = 180mg/dl or higher

Two Hours = 155 mg/dl or higher

Three Hours = 140 mg/dl or higher

See More:
3 Hour Glucose Tolerance Test
Eating and Taking Gestational Diabetes Test

Diagnosed with Gestational Diabetes

If you are diagnosed with gestational diabetes, your doctor will come up with a diet and exercise plan to manage your condition, which should only last as long as your pregnancy.  A small number of women who develop gestational diabetes may still have it after delivery.  You will need to repeat the glucose test about 6 weeks postpartum.

In addition to the above screening tests, more tests may include:

• Glycosylated hemoglobin (HbA1c)— A blood test which reflects the cumulative changes in your blood sugar over the last three months
• Urine tests—protein (24-hour collection) for ketones
• Thyroid function tests:  TSH and free thyroxine test
• Tests to check the fetus— Ultrasound (usually done at 30-32 and 36-38 weeks), counting of fetal movement, amniotic fluid analyses

The Importance of Testing

Since diabetes leaves glucose in your blood, it can expose your baby to an increased level of sugar for a longer period of time.  Most likely your doctor will place you on a low carbohydrate diet to manage your glucose level.  If you have severe gestational diabetes then you may have to take insulin, in addition to eating a low carbohydrate diet.
Having gestational diabetes can lead to a more difficult birth due to the size of your baby, as your baby may be quite a bit larger due to the diabetes.  If the baby is found to be too large for vaginal delivery, a C-section may be performed.

After the birth, it’s actually highly recommended for moms to breastfeed the baby to maintain their sugar levels.
Pregnancy is an excellent opportunity to discover if you are genetically programmed to develop diabetes later in life. It’s a good idea to keep up with good eating habits, exercise and keeping your weight at healthy levels to avoid getting the disease altogether.

Gestational Diabetes Testing Results

3-Hour Glucose Test

Normal blood values for a 100-gram oral glucose tolerance test used to screen for gestational diabetes:

3 Hour Gestational Diabetes Glucose Tolerance Test

Read More:  Following a Diet Plan with Gestational Diabetes

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