Gestational diabetes: Glucose Challenge Test (GCT) & Glucose Tolerance Test (GTT)

WHAT is gestational diabetes?

Gestational diabetes is the temporary onset of diabetes, a condition that affects your body's ability to effectively process sugar, that sometimes occurs during pregnancy. Gestational diabetes is among the most common pregnancy complications, and although there is no magic cure, it can very much be managed by diet, exercise and occasionally medication. Most women will notice their gestational diabetes disappear after they give birth.

WHY do I need a Glucose Screening/Challenge Test during pregnancy?

Most healthcare practitioners routinely recommend a glucose screening test (also called a glucose challenge test or GCT) between 24 and 28 weeks of pregnancy to check for gestational diabetes.

Gestational diabetes is a high blood sugar condition that some women get during pregnancy. Between 2 and 5 percent of expectant mothers develop this condition, making it one of the most common health problems during pregnancy. And because the condition rarely causes any symptoms, testing is the only way to find out whether you have it.

Like any screening test, the GCT won't give you a diagnosis. Instead, it's designed to identify as many women as possible who may have a problem and need more testing to find out. So a positive result doesn't mean that you have gestational diabetes.

In fact, only about a third of women who test positive on the glucose screen actually have the condition. If you test positive on the screening, you'll need to take the glucose tolerance test (GTT) – a longer, more definitive test that tells you for sure whether you have gestational diabetes.

Your practitioner may want you to be screened earlier than 24 weeks if a routine urine test shows a lot of sugar in your urine or if you're considered high risk. If the results are normal, you'll be screened again at 24 to 28 weeks.

Of course, if you were diagnosed with diabetes before pregnancy, you won't need to be screened. Instead, you'll continue to work with your practitioner to manage your condition during pregnancy.

HOW is the Glucose Screening/Challenge Test done?

When you arrive for the test, you're given a sugar solution that contains 50 grams of glucose. The stuff tastes like a very sweet soda pop (it comes in cola, orange, or lime flavor), and you have to get all of it down in five minutes. Some centers keep it chilled or let you pour it over ice and drink it cold.

An hour later (bring something to read or play game on your mobile phone!), a blood sample is taken from your arm to check your blood sugar level. The idea is to see how efficiently your body processes sugar. The results should be available in a few days.

If the concentration of sugar in your blood is greater than 140 mg/dL, your healthcare provider will probably recommend the Glucose Tolerance Test.
(If the reading is too high, which happens 15 to 23 percent of the time, you'll be asked to come back for a three-hour glucose tolerance test to see whether you really do have gestational diabetes. The good news is that most women whose screening test shows elevated blood sugar don't turn out to have gestational diabetes.)

HOW is the Glucose Tolerance Test done?

The exact procedure varies, but typically you're instructed to eat a late meal the night before the test. After that you may be told not to eat or drink anything but sips of water, so you'll want to schedule the test for first thing in the morning.

When you arrive for the test, a blood sample is taken to measure your fasting blood glucose level. Then you drink either a more concentrated dose or a larger volume of the glucose solution. At that point, brace yourself for two or three more arm pricks, as your blood is tested every hour for the next few hours. The technician should alternate arms each time your blood is drawn.

You'll definitely want to bring something to distract you, because you have to stay seated in the waiting room when your blood is not being drawn. Also bring something to eat right after the final blood sample is taken, because you'll probably be starving.

Your blood sugar is considered high if it is over 180 mg/dL at 1 hour, 155 mg/dL after 2 hours, and 140 mg/dL after 3 - if you fail any two of these your healthcare provider will probably diagnose you with gestational diabetes.

Prognosis

Although gestational diabetes can be a serious complication of pregnancy, most women who develop it give birth to perfectly healthy babies and remain healthy themselves - it's most important to follow your healthcare provider's instructions if you are diagnosed with gestational diabetes in order to most effectively manage it.

My Glucose Tolerance Test at 26 weeks

So well, for me, I didn't go for the GCT. When I was at KKH for my last appointment, they scheduled me this week to take the GTT (Glucose Tolerance Test). The appointment was set at 8.30am. But I was so sick (flu, cough, asthma attacks) that I didn't feel like going all the way down to KKH, that far. So I missed the appointment, but I headed down to Regional Patientcare Medical Clinic (Admiralty Branch) at 10.30am to take the GTT there instead. (Please call the GPs to check if they have the glucose stocks for GTT before heading down for walk-ins as most GPs need to order in advance).

I had a total of 3 pricks.
First blood sample was taken when I first arrived at the clinic (fasting blood).
Given a bottle of glucose drink to finish within 5 minutes.

Returned to the clinic to have my second blood sample taken 1 hour later.
And then had my third blood sample taken another 1 hour later.
I WAS REALLY STARVING THROUGH OUT.
Couldn't wait to have my first bite after the end of GTT.

Price Comparison
My private gynae charges GTT at $150 (excluding gst).
GTT at GPs (General Practitioners) would cost only $30-$40 (excluding gst).
I'm not sure how much KKH charges for GTT as i missed the appointment (would be nice if someone can comment and share the cost so i can update).

Total Damage: About $55-$60 (includes consultation fee)

My GTT Result Update (18/5/2018):

According to the Guideline, my result appears to be on the higher than normal side. But when I showed this result to my Gynae, he said that it is PERFECT. And I felt so relieved right after.