The Oral Glucose Tolerance Test: Being a physician doesn’t free me from the trappings of pregnancy!

Today I learned that I did not pass (ok, failed) my 1-hour glucose challenge test.  More than that, I failed “badly” according to my OB/Gyn. Apparently not badly enough that I have gestational diabetes (GDM), but I learned that I do have to go through the 3-hour glucose tolerance test.

So what does all this mean?

Rather than rehash too much information that has already been written elsewhere, I will go more specifically to the questions that I was concerned about:

How likely is it that I have gestational diabetes?
It’s important to remember that the 1-hour glucose challenge test is a screening test, meaning that while there are 2-3% of pregnant women who end up having GDM, it’s a catch-all test that screens for all women at risk. That being said, if you end up with a 1-hour blood sugar level of 190, there is a 90% chance that you have GDM. In other words, you are basically diagnosed with gestational diabetes and don’t  go through the 3-hour test. But levels between 140 and 190 are considered concerning for GDM. Around 20% of patients with an abnormal 1-hour screen will go on to have GDM when they go through the 3-hour test.  So I am crossing my fingers, but if my numbers were high in the first place I am worried!

If I have a positive 1-hour test, and [hopefully] a negative 3-hour test, is there any risk of problems with my baby regarding gestational diabetes?
I checked out the studies available on PubMed regarding this relationship. From what I see, patients who have a positive 1-hour test and go on to have a negative 3-hour test don’t have any increased likelihood of harm to the fetus.

Can the test result numbers predict that I will have a large fetus because of gestational diabetes?
Unfortunately, no – there is no specific level of blood sugar on a glucose tolerance test that will be more predictive of the size of a fetus.

What’s the chance that I will have diabetes in the future?
Unfortunately, 40-60% of women who have gestational diabetes go on to develop diabetes mellitus in their later years, so if I do end up having it, it is reason to be extra careful in the time to come.

And I know that I have tons of more questions that I did do some reading about, but it is getting late and I need to at least attempt some sleep.  Pregnancy, this darn infection, and general fatigue are catching up with me.  I attempted a workout yesterday that pretty much just got me very tired, and tomorrow I have to defer my workout. Gotta get this body back in gear if I want to be able to continue preparing for baby! Needless to say, I am pretty nervous about this medical screening process. It is tremendously frustrating to do everything you can during pregnancy – read everything, eat right, get regular exercise even in the face of pediatric boards, start a new job, spend time with my husband – and then find out that things aren’t working out according to plan. I am crossing my fingers for next week.

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A pediatrician. Now turned first-time mom. Venting and giving you all the wisdom I acquire over the days . . .

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4 comments on “The Oral Glucose Tolerance Test: Being a physician doesn’t free me from the trappings of pregnancy!
  1. N says:

    What was your number? I meant to ask you that on FB, but forgot. Many many folks fail the one hour and pass the 3 hours, though – and it’s not even necessarily based on your number. I was pregnant with a woman (on her third pregnancy) who failed her 3 hour test in both her 2nd and 3rd pregnancies, but on the one hour test, would only *just* have been considered “failed.” And there were folks whose numbers were high on the one hour test, but then passed the three hour test. So I guess you never know… Fingers crossed you pass the three hour, but it’ll be no fun either way. (longest I’ve ever done was a two hour, not while pregnant, but testing for insulin resistance, and man, I was ready to kill people and eat a whole chicken when I got out of there.)

    • SingingDoc says:

      I’ll send you my number, thanks for reading my post, btw!! I really hope i pass the three hour test. i hated fasting for the one hour test, lemme tell you, and i followed up last week’s trip with yogurt, fruit, cheese, and a reward trip to the mall to round out my fall maternity clothes! What I worry about is that my sugar was high even with fasting. But we will see. . .

  2. Wangus says:

    Take heart, doc2mom!