Of all the tests pregnant women are expected to endure, glucose testing is probably the most dreaded. Women groan, and tell me they’ve heard horror stories from their friends about how sick the drink will make you feel, or how they couldn’t hold it down. There are two types of glucose tests. The first involves drinking a sugary, flat soda type of drink (called a glucola), then getting your blood sugar levels drawn one hour later. This is a screening test only, and helps practitioners decide who needs the three-hour test. The three-hour test involves drinking a sugary drink on an empty stomach (after fasting 12 hours), and getting four blood draws: one before you drink the glucose; and subsequent draws at one, two, and three hours after drinking the glucose. Having elevated blood sugars on any two of these four draws confirms a diagnosis of gestation diabetes.
The mystery to me is why glucose testing continues to be performed on nearly ALL pregnant women, regardless of risk factors. The American Diabetes Association recommends categorizing women into high-risk, average-risk, or low risk groups.
High risk women are those who begin pregnancy with a high body mass index (BMI), have a personal history of GDM, or have a strong family history of diabetes. Other risk factors include older maternal age (over 35) and African-American, Native American, or Hispanic ethnicity. These women should be screened in early pregnancy, and again at 24-28 weeks.
Low-risk women, who do not need to be screened, are under age 25, normal weight at onset of pregnancy, do not belong to a higher-risk ethnic group, and have no personal history of GDM, poor obstetric outcome, or family history of diabetes in a first-degree relative.
Women of average risk, who are not in the high risk category, but don’t meet all the criteria for low-risk women, should be screened at 24-28 weeks.¹
However, evidence to support these recommendations is lacking, according to the Cochrane Review and the United States Preventive Health Taskforce (USPHT). The USPHT recommends, “Until there is better evidence, clinicians should discuss screening for GDM with their patients and make case-by-case decisions. Discussions should include information about the uncertainty of benefits and harms as well as the frequency of positive screening test results.”²
When is the last time a pregnant woman receiving typical modern obstetric care was treated on a case-by-case basis? Most women are treated with cookie-cutter, one-size-fits-all obstetric care.
A recent study found that testing fasting blood sugar by a simple finger-stick (which a woman could do herself at home) may be just as predictive of women who need a three-hour glucose screening as the one-hour test.³ Additionally, there are other tests which are alternatives to the one-hour test, and may be more appealing to some women.4 These tests include a pancake breakfast, or eating a specified number of jelly beans. Concerns about these tests as substitutes are that they may not be as accurate as the one-hour glucose in predicting which women need the three-hour test, but they are used in government health agencies, including the Indian Health Services, which serves a high-risk population.
Many of my clients say to me, “I don’t eat refined foods when I’m pregnant, so why should I drink a big glass of refined sugar?” The politically correct answer is, “So we can have an ‘approved’ diagnosis of gestational diabetes.” But many women would prefer not to take the glucola test, especially if they are already very health-conscious and physically fit.
I have also worked with clients by loaning a glucose meter that is calibrated to simulate identical blood sugar levels as when you get your blood drawn from your arm. They can check a fasting blood sugar when they first wake up in the morning, and then blood sugars two hours after a typical meal, on two or three different days and times. I believe this provides a more accurate picture of how the woman’s body is handling her normal diet, although I admit it does not give us the “official” diagnosis of gestational diabetes.
Common-sense tip for today: Talk with your provider about the USPHT recommendations. Are you at increased risk for GDM? Then consider testing, whether it is glucola or an alternative. Are you at low or average risk? You may wish to consider skipping testing, unless it seems that the baby is growing faster than usual, you are having consistent problems with sugar in the urine, or you are experiencing symptoms such as jitteriness/dizziness/nausea.
1. American Diabetes Association. Gestational diabetes. Retrieved 03/25/10 from: http://www.diabetes.org/diabetes-basics/gestational/
2. National Guideline Clearinghouse. Screening for gestational diabetes mellitus. Retrieved 03/25/10 from: http://www.guideline.gov/summary/summary.aspx?doc_id=12507&nbr=6437&ss=6&xl=999
3. Agarwal MM, Dhatt GS, OthmanY, Gupta R. Gestational diabetes: fasting capillary glucose as a screening test in a multi-ethnic, high-risk population. Diabetic Medicine, 2009. Retrieved 3/13/10 from: http://www.ncbi.nlm.nih.gov/pubmed/19709144?dopt=Abstract
4. Indian Health Services. Alternatives to oral glucola testing. Retrieved 03/15/10 from: http://74.125.95.132/searchq=cache:EWcHFJkuecMJ:www.ihs.gov/MedicalPrograms/MCH/M/documents/AltGlu4505.doc+IHS+alternative+glucose+testing&cd=1&hl=en&ct=clnk&gl=us
I know I post here often, but I do want to say your blog is absolutely AWESOME. I pass it along to so many people, and I certainly hope it helps change the dialogue.
There have murmurs in the birth community about moving to a 2 hour glucose screening for everyone. Have you heard of this? Thoughts?
I second Veronica’s comment. Your blog is fantastic. Long live the community midwife!!
Thanks, Jill! I’m a great fan of your blog, as well.
Thank you for your kind words. I hope the blog is reaching some people who otherwise wouldn’t think twice about these things. There seems to be such a lack of interest on the part of many women in having a normal birth.
The two hour test is an older test. The “cutoffs” for normal fasting blood sugar used to be higher, and the two hour test was better at identifying those who needed additional testing. Since the threshold for abnormal fasting glucose has been lowered, the one-hour seems to be accepted as being just as accurate for a screening test. Different areas use different tests, though. I’ve worked in all areas of the country, and find that practices can vary greatly region to region.
Great post! When I was pregnant with my daughter, I did the one hour glucose testing at 24 weeks – result was BEYOND normal – expected range was 100-130, mine was 62 and I felt like I was going to pass out at the end of it. When I got my ultrasound just four weeks later, my daughter was measuring very large so they wanted to check it again! I tried to refuse it, but my OB insisted and they can be hard to argue with, so I finally took it again. The result – 60. Absolutely ridiculous!!
What my confusion is over is how different OBs administer the tests. When I had to take the one hour my OB asked me NOT to fast and just to eat and drink like I would normally. Others I have talked to were told to fast for hours or even overnight before the test.
The policies on how to administer the test can vary from one hospital or OB practice to another. Different labs have different requirements. In most of the areas where I’ve worked, the one-hour test did NOT require the woman to fast prior to taking it. In other areas, we did have the women fast. The three-hour test, to my knowledge, has always been done following at least 8-12 hours of fasting (nothing to drink but water or plain black coffee). Some practices also asked the women taking the three-hour test to eat a special diet high in carbohydrates for three days prior to the test.
Ugh, the GD test. I have passed the 1 hour test with both pregnancies. This time around I have an Insulin Resistance diagnosis under my belt. They’ve been having me test my blood sugars several times a week for months. I have not had high blood sugras at all, I am overweight but have recently lost 30 pounds and am having a very healthy pregnancy. YET, they still made me do that freaking test. Both times I’ve taken it I’ve been told to fast for 12 hours beforehand. I was SO hungry by the time it was over. I was told by my endocrinologist that you are really only at risk for gestational diabetes if you have insulin resistance. Makes me wonder why people who don’t have that are made to do this test.
Because it’s easier to make everyone do it than try to work with women on alternative ways of monitoring blood sugar or risk for elevated blood sugar. It’s also partly a CYA thing–if a provider doesn’t test for gestational diabetes, and the baby ends out being large for gestational age, s/he may be more likely to face a potential lawsuit.
The problem is that the GTT under any guise is completely inaccurate. The whole idea of carb-loading (no matter what kind of carbs you use) and then testing the mother’s blood sugar levels is still putting the mother’s body through a type of metabolic gymnastics that does not reflect what she is doing in her real life. In addition, the GTT has been shown to be utterly unreliable due to the fact that it is so vulnerable to being skewed by anything which causes the mother to secrete adrenalin, like fear of needles, fear of the consequences of the test results, having been caught in traffic and fear of being late for the appointment, having to deal with kids fighting in the car, stress at work, stress in the marriage, etc, etc…I always recommend that mothers ask for the “Hemoglobin A1C” instead of the GTT. For more information, including links to articles by Dr. Michel Odent and Henci Goer, you can see my website page on “Gestational Diabetes”
http://www.drbrewerpregnancydiet.com/id33.html
Thanks for including these links. Hemoglobin A1C shows an average of blood sugar over the past three months or so. The reason I have been told not to use it for diagnosing gestational diabetes is that many women will not begin to have elevated blood sugars until 24-28 weeks of pregnancy. Because the Hgb A1C averages blood sugars over a period of time, it could be late in the pregnancy before blood sugars have been elevated for a long enough period of time to cause the Hgb A1C to be abnormal. By that time, the baby could already be very large and at increased risk of complications after birth due to the mother’s gestational diabetes.
Joy, I agree that during pregnancy, the normal physiologic state is changed from that of the non-pregnant woman. In early pregnancy, the body is more sensitive to insulin than usual, allowing maternal fat stores to be built up, preparing the body for the very rapid period of fetal growth to come in the second half of pregnancy. During the later stages of pregnancy, the body becomes insulin resistant, in large part due to hormone produced by the placenta. This insulin resistance has the effect of increasing blood sugar, providing more glucose for fetal growth. With this said, I don’t think the A1C is a good test for gestational diabetes. Since it reflects an average of blood sugar levels over the past 3-4 months, as what point in pregnancy would we use this test? Since the normal pregnant body does not become insulin resistant until about the third trimester, if excessive insulin resistance–and consequently, abnormal blood sugar levels–did exist, at what point would the A1C reflect this situation? The state of hyperglycemia would have to exist for at least 3 months before an A1C would indicate the problem; if the hyperglycemia began around 28 weeks, the pregnancy would be full term before the problem was detected. I do agree that the screening and diagnosis of GDM is grossly overused, but I also am convinced that the condition does exist. One reason for its existence is the poor diet and frequency of obesity in pregnant women today. We know this predisposes women to diabetes and gestational diabetes. I have a personal experience with a friend who had GDM, and had successively larger babies, until her last home birth was a 12 pound baby who nearly was not delivered due to severe shoulder dystocia. My friend’s midwife did not believe in gestational diabetes, yet both my friend and the baby were clearly affected by this condition. While I believe it is overdiagnosed, I also believe it is irresponsible to say that there are no large babies due to hyperglycemia in mothers.
This really is one of the worst trests! And – seriously, when is anyone, let alone a pregnant woman going to drink something like that in normal life. Blech!
Passing this along via Facebook!
Exactly. I just had a woman ask me today why she is expected to remain still for the hour following the exam, when she never sits around for an hour after eating normally. Exercise will cause the glucose to be better metabolized, so they want you to laze around so that will not occur.
When you read the articles by Henci Goer and Michel Odent (linked to through the page that I posted earlier), you will see why the concern about large babies and pregnancy/labor complications is pretty unfounded. What has been done is that the complications that are experienced by women with UNCONTROLLED, Type I diabetes are being extrapolated and hypothesized to exist in women and pregnancies with “gestational diabetes”. Many of us believe that this hypothesis is not based in scientific fact. Thus our concern with using a test that one author in an internal medicine text described as SO prone to false positives that it should never be used in clinical practice, and that it should only be used for research purposes. Therefore, it seems to me that the A1C is still the more reliable test, if we are to use any screening test for GD during pregnancy at all. After all, the placenta is actively working to produce higher blood sugars during pregnancy than women have during their non-pregnant states. How can we dare to question the placenta, which has successfully sustained the human race for thousands of years? To do so would seem to be insisting that the pregnant body follow the same standards as the non-pregnant female body, or the male body.
I don’t understand why ANY of the sugardrink tests are EVER performed! The only way to really know how the body is managing sugars is by doing a blood test called hemoglobin a1. this tells the doctor how your control has been for the past three months and is used on all us diabetics all the time. it’s simple, dead easy and ACCURATE, where none of the sugar drink tests are reliable at all! false positives and negatives happen CONSTANTLY! why not take one vial of blood and do the PROPER test?
During my routine examination after I drank the gross bottle of sugar water, they immediately took me to measure the baby’s heart rate. They were astounded at the high reading of the baby’s heart rate, and I was like Duh! You just gave her a sugar high! Think people! They measured it again later, and she had crashed just like I did.