What is gestational diabetes?
In short, gestational diabetes (often abbreviated GD) occurs in women who were not diabetic pre-pregnancy, but who have high blood sugar levels during pregnancy. This happens because pregnancy hormones can interfere with the production of insulin, which is what helps your body process sugar.
If your blood sugar levels remain high, the extra sugar gets transferred to the baby. This can potentially cause a whole host of problems with the pregnancy.
Here is a good article that explains more and also links to a short CDC podcast about GD: http://www.diabetes.org/diabetes-basics/gestational/what-is-gestational-diabetes.html
With Littles and Noob
With both of the older kids, at around 24 weeks, I had what is often called the "one hour" test. I had to drink a soda-like beverage with a certain amount of sugar in it. One hour later, I had a blood draw to check on my sugar levels. In my case, my sugar levels were low enough to indicate that my body had properly processed the sugar in the drink.
If they had been too high, I would have gone on to take a three hour oral glucose tolerance test (OGTT). Same lovely drink, except during an OGTT, the patient gets blood draws before drinking the drink and then every hour for three hours afterwards. Usually, having two out of the three draws above the acceptable thresholds results in a GD diagnosis.
Most women with GD are able to treat it successfully through diet, by eating regularly, eating more complex carbohydrates/fewer simple sugars, boosting protein, etc. This article includes some general guidelines for diets for women diagnosed with GD.
Still, in a typical hospital-based practice, women diagnosed with GD are classified as "high risk," even if their glucose levels remain well-controlled with diet. GD patients are generally subjected to more interventions, such as regular growth scans and NSTs, early induction (to prevent the baby from getting too big), etc.
With Q
C doesn't generally do the one hour test. Instead, at my 30-week appointment, she did a finger prick to check on my glucose levels. Mine were fine (actually on the low side!), so no GD concerns.
Why the different approach? Well, I'm sure part of the reason is that it's much simpler, given that the one hour screening generally has to be done by an outside lab, and C is not able to write lab orders. She can do the finger prick right in her office. Easy. And I just have to eat normally, rather than drinking that icky soda stuff. Easy, too.
Of course, easy isn't always better... but in this case, I think it is! For starters, it's exactly how women diagnosed with GD monitor their blood sugar levels. And again, most women diagnosed with GD are able to control their blood sugar levels with diet. So it makes sense that if your blood sugar levels are within normal range after eating your normal diet, then your normal diet is doing a good job of, well, controlling your blood sugar levels!
To that end, I've also found that C talks to me a lot more about my diet than any of my previous providers. At pretty much every appointment, actually. Really, a "GD diet" is nothing revolutionary; most pregnant women would benefit tremendously from choosing more protein and complex carbs over simple sugars, regardless of GD status. (Heck, most people would benefit from making those choices in general, regardless of pregnancy status :) C, and many homebirth midwives, tend to steer all of their patients towards that type of diet early on, rather than waiting till they fail the OGTT.
Also, C's more personalized approach to prenatal care shines through here. At every prenatal appointment I've ever had, I've had to do a urine test, which screens for sugar in my urine, among other things. Sugar in the urine can be an early sign of a woman whose body is having trouble processing sugar. With my previous providers, I always gave my urine sample to a lab person who never saw my face. With C, I give the dipstick directly to her.
This means that she quickly gets an idea of what is "normal" for me and what is not. For example, at my last appointment, she looked at the stick and said, "What did you eat for breakfast?" I told her: cereal, yogurt, and orange juice. (That's another way she can get a sense of my dietary habits.) She said, "OK. Your sugar levels are higher than normal for you. They are not too high, it's just that you're normally below the normal range, and today you're in the normal range. But it was probably the OJ." That is an analysis that an anonymous lab person who never saw my face never could have made.
(Interestingly, my previous providers never mentioned any concerns about the sugar levels in my urine. Not once. C has now mentioned something twice this pregnancy. The first time was a few months back, after I had a handful of gummy worms with my lunch. I don't know if her test is more sensitive, or if that just goes back to the fact that she knows that being in the "normal" range is not normal for me.)
So it all fit together: C knew my diet, and knew that it was generally good. She knew that I rarely spill sugar in my urine. And so when my blood sugar levels on the finger prick test were low as well, she was able to say pretty confidently that I don't need any further GD testing.
Of course, had she had any concerns, she would have asked me to get an OGTT. If that test diagnosed me as a gestational diabetic, I would have been able to stay in her care as long as I kept my blood sugar levels under control with diet. If I got to the point where I needed insulin to control my blood sugar levels, I would have risked out of homebirth.
Differing perspectives on GD screening and diagnosis
The 1-hour test is widely considered to be "the" way to screen for GD, so much so that I've heard many people say that it's foolish or downright dangerous to not do the 1-hour test. But the 1-hour test is just one of several screening methods that the American College of Obstetricians and Gynecologists (ACOG) recommends:
"All pregnant women should be screened for GDM [gestational diabetes mellitus], whether by patient history, clinical risk factors, or a 50-g, 1-hour loading test to determine blood glucose levels."
So, C's finger prick test is right in line with those recommendations.
For diagnosis, ACOG recommends the 3 hour OGTT. Again, C does recommend the same if she has concerns about one of her patient's blood sugar levels.
Furthermore, there is some disagreement over whether the OGTT is even an appropriate way to diagnose GD. On one side of the spectrum, there is Henci Goer, who argues that the OGTT and diagnosis of GD in general is useless: http://www.gentlebirth.org/archives/gdhgoer.html
It's an interesting read, but I should point out that 1) Henci Goer is not a doctor and is strongly anti-intervention, so she's hardly an unbiased source, and 2) the sources she cites are fairly old, with the most recent being from 1994.
On the other side of the spectrum, a large-scale 2008 study, called the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study, suggested that the current diagnosis criteria may not be stringent enough! http://www.nejm.org/doi/full/10.1056/NEJMoa0707943
In short, the HAPO study followed women who were not diagnosed as GD under the current criteria. It found that the risk of a number of adverse pregnancy outcomes (such as macrosomia, primary c-section, shoulder dystocia, and pre-eclampsia) rose linearly in correspondence with the mother's glucose levels during a 2-hour OGTT.
This led the American Diabetes Association (ADA) to recommend revised guidelines for diagnosis of GD: http://care.diabetesjournals.org/content/34/Supplement_1/S11.full#sec-11
Again, to summarize: The ADA recommends getting rid of the two-step screening-diagnosis testing (the 1-hour and 3-hour tests), in favor of a single 2-hour OGTT for all women. While ACOG's standards only diagnose a patient as having GD if she has two or more blood draws indicating glucose levels above the defined thresholds, the ADA guidelines call for a GD diagnosis if there is a single draw with glucose levels above the defined thresholds. This would substantially increase the number of women diagnosed with gestational diabetes.
"because there is no evidence that diagnosis using these criteria leads to clinically significant improvements in maternal or newborn outcomes and it would lead to a significant increase in health care costs."
So what to make of all this? I actually think it can all be rationalized.
Let's start with the ADA guidelines. Despite calling for revised diagnosis criteria that would increase the number of women diagnosed with GD, they do concede that we don't really know exactly how these women with "mild" GD should be treated:
"Additional well-designed clinical studies are needed to determine the optimal intensity of monitoring and treatment of women with GDM diagnosed by the new criteria (that would not have met the prior definition of GDM). It is important to note that 80–90% of women in both of the mild GDM studies (whose glucose values overlapped with the thresholds recommended herein) could be managed with lifestyle therapy alone."
What kind of "lifestyle therapy?" Well, maybe the answer can be found in Goer's article, of all places:
"Pregnancy makes extra demands on insulin production; to minimize the pressure, pregnant women should eat a diet low in simple sugars, high in complex carbohydrates and fiber, and moderate in fat. Moderate, regular exercise also improves glucose tolerance."
In other words, the key isn't so much how we diagnose GD, but how we treat it. There is no doubt that there are some women with high sugar levels during pregnancy who need aggressive intervention. Even C concedes this, by risking women out of homebirth if they need insulin to control their diabetes. Heck, even anti-interventionist Goer concedes this: "Within the GD population lurk a few women who were either undiagnosed pregestational diabetics or who were tipped into true diabetes by the metabolic stress of pregnancy; a fasting glucose to screen for them might be prudent."
But most women with GD probably don't need aggressive intervention, just some form of intervention, such as nutritional counseling. Beyond that, they just need to be treated like the healthy pregnant women that they (mostly) are. As C puts it: "If you are diagnosed with GD, but you're able to control your glucose levels with diet alone, you don't really have GD."
Personally, I'd love to see the HAPO study repeated, with a twist: Rather than just following women after their 2-hour OGTT, divide them into two groups, with the control group just being followed and the test group receiving in-depth counseling on nutrition, exercise, etc. If my previous paragraph is correct, the outcomes among the test group should be better than the outcomes among the control group, regardless of the original glucose levels.
That would also be a fascinating confirmation of C's approach to GD screening and "treatment," too, since she essentially does that type of counseling with all her patients. As I said in my introduction to this blog, homebirth is not just like hospital birth except you stay at home at the end. It is a completely different approach to prenatal care as well, and this is a great example of that.
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