Gestational Diabetes Mellitus (GDM), part 1 – Screening/Diagnosis

Gestational Diabetes Mellitus (GDM) – diagnosis

Pregnancy can be difficult enough without the challenge of an added complication like gestational diabetes to make you worry about harming your unborn child and setting yourself up for a difficult and/or dangerous labor & delivery experience.  If you’ve received the diagnosis of gestational diabetes or have been told that you are at risk for it, please know that it can be easily managed by adjusting your diet, so long as you don’t follow the conventional dietary advice recommended by a traditional dietitian.

Why do we care about GDM?

The major fear of gestational diabetes is that baby is exposed to an unnaturally high level of glucose from mom.  There are potentially serious complications that can result from high glucose exposure in a dose-dependent fashion (the higher and longer the glucose is elevated, the more complications will result).  Complications include increased birth weight and shoulder dystocia, infant hypoglycemia immediately after birth, and more long-term effects such as an increased risk of insulin resistance and diabetes later in life for the infant.  High glucose is a teratogen – a substance that has toxic effects on a baby in utero.


Diagnosis of GDM

For starters, let’s talk about how gestational diabetes is diagnosed.  The typical approach is to administer a large dose of sugar, in the form of glucose – 50 gm for the initial screening test, then 100 gm for the second confirmatory test.  Alternatively, a single 75-gm glucose test may also be an option.  Just how much sugar is that?  The American Heart Association recommends that women consume no more than 25 gm of sugar daily, and the Dietary Guidelines for Americans 2015 report advised no more than 10% of calories to come from sugar, which equals 50 gm of sugar in a 2,000-calorie diet.


Sometimes the diagnostic test is just as bad as the disorder.  Giving sugar to a pregnant woman to determine whether she is carbohydrate-intolerant is the equivalent of giving alcohol to a pregnant woman to determine if she can metabolize alcohol quickly enough to avoid exposing baby to any alcohol.  Right…it doesn’t make any sense that the diagnostic test is as harmful as the disease process you’re testing for.

I completely understand why the old guard of OB/Gyn’s insists on doing the Glucose Tolerance Test: it’s simple (to THEM…they’re not the ones drinking the poison) and it gives them a concrete result to put in their chart that makes them feel good about the care they’re providing and gives them reassurance that they won’t be liable for any possible bad outcome since they “followed protocol”.  It’s part of the CYA (Cover Your A**) approach to medicine that has sadly evolved as defensible medicine was tossed aside in favor of defensive medicine.  Just another contributor to the outrageous expense (and poorer outcomes) of US healthcare.


So your doctor tells you that you have risk factors for Gestational Diabetes Mellitus (GDM) and that you must have a Glucose Tolerance Test (GTT).  Quite frankly, they are basically doing the GTT on everyone these days, because living in the US and eating a Standard American Diet (SAD) are essentially risk factors alone for GDM.  But, you may have been overweight or obese at the start of your pregnancy, which further increases your risk.

Why not do the Glucose Tolerance Test

If you are already eating a low-carbohydrate diet, you will almost assuredly fail the glucose tolerance test, as there is essentially a downregulation of glucose/carbohydrate metabolism when you are not consuming typical amounts of glucose/carbohydrates.  [It is slightly more complicated than this description, but simply put: All carbohydrates break down into glucose.]  Thus, you become sensitized to the effects of glucose, so consumption of a large slug of glucose as given in the Glucose Tolerance Test will definitely result in excessive hyperglycemia – a failing grade.  This principle has been observed repeatedly, examples here and here.

Furthermore, high glucose is a teratogen – a substance that poses a hazard to baby in utero.  It’s the equivalent of giving a pregnant woman a shot of alcohol to see if she can metabolize it before it reaches baby – give a known teratogen and see how well mom metabolizes the toxin, all the while hoping that it won’t reach baby and cause harm.  Pure nonsense…it’s amazing to me that this test is even allowed.  But, it’s only one incidence of unnecessary glucose exposure?  Actually, it would be two, including the follow-up confirmatory test with double the dose of the first.  If you’re not concerned about “just one” exposure, why not “just one” binge on alcohol during your pregnancy?  Or “just one” exposure to some other known teratogen during pregnancy – thalidomide anyone?  I’m not saying that one or two incidents of hyperglycemia will have notably negative consequences, but tolerating an unnecessary exposure gives the wrong message about self-care in pregnancy.  Furthermore, we simply don’t know everything there is to know about the human body – it may be that one episode of hyperglycemia does actually cause irreparable damage…we just don’t know.

Alternatives to the glucose drink

Some women refuse to use the standard Glucola drink, instead opting to ingest something else to provide a similar sugar load, like jelly beans, fruit juice, or some other concoction.  They’ve totally missed the point.  No matter what the source of carbohydrate, the effect will be the same – potential toxicity to baby in the form of high glucose.  This concept is not breaking news – it’s basic physiology.  All carbohydrates break down into sugar.  It doesn’t matter what form it takes, all carbohydrates are digested into sugar.

Instead of the traditional Glucose Tolerance Test, I recommend a more proactive approach of monitoring one’s own glucose at home, with a simple glucose meter.  Measuring fasting glucoses and 1-hour postprandial (1 hour after the meal) glucoses provides even MORE useful information about a woman’s glucose tolerance, as it better demonstrates a real-life response to an actual meal [unless your typical meal is a 20-oz bottle of juice or regular soda].  Furthermore, it provides instant feedback about the effect of specific foods on one’s glucose, a learning tool that is perhaps the most powerful intervention of all in managing nutrition-related diseases.  If your glucose rises in response to a certain food, e.g. oatmeal or a banana, then those are foods to restrict or avoid for the remainder of your pregnancy.  Is there actual scientific evidence to support this approach?  I’m not sure, but I do know that fingerstick glucose monitoring is the mainstay of monitoring GDM once it’s diagnosed <>, and maintaining normoglycemia (normal blood glucose) is ultimately the goal of management of GDM.  Therefore, if you can demonstrate that your glucoses are consistently in the normal range, you have successfully demonstrated that your pregnancy is not at risk from GDM.

Obviously, you will need to discuss this screening option with your obstetric care provider.  Remember that you are your own best advocate, and thus you need to do the research before you get thrust into doing tests or interventions that you don’t understand.

How to treat/prevent GDM? (part 2 of 2)


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