As a specialist in gestational diabetes nutrition, I get a lot of questions about blood sugar and pregnancy.
Gestational diabetes is controversial. It’s complicated. And there’s a lot of misinformation out there.
I do my best to address the controversies in interviews and with participants in my online gestational diabetes course, but since I’ve been receiving more and more inquiries in my inbox from fellow healthcare professionals, I wanted to dispel some gestational diabetes myths head-on right here on the blog.
I’ll also be attending some midwifery conferences this year (including one this weekend), and I figured this resource would be a helpful place to refer practitioners if they have questions.
Given the medical interventions that are commonly pushed on women with gestational diabetes (believe me, I’m also disheartened by the over-medicalization of pregnancy and birth), it’s important to understand the science behind high blood sugar and pregnancy.
My goal is to help moms and practitioners make better decisions – based on fact, not fear – so they can have the healthiest pregnancy possible.
9 Gestational Diabetes Myths
Myth #1: Blood Sugar Levels are Naturally Higher In Pregnancy
There’s a lot of misinformation floating around about blood sugar levels in pregnancy. Some think that gestational diabetes is a “diagnosis looking for a disease.” In other words, they believe that blood sugar levels naturally go up during pregnancy, so there’s nothing to worry about.
Some practitioners don’t even test for gestational diabetes and just tell their patients to “eat healthy” under the assumption that any rise in blood sugar is just a normal phenomenon of pregnancy.
Unfortunately, that’s not true. Research has looked at blood sugar levels in normal, healthy pregnant women and found that blood sugar levels consistently trend 20% lower than blood sugar in non-pregnant women. (Diabetes Care, 2011)
Read that again: 20% LOWER.
This is why there’s so much confusion when you hear about the “low” blood sugar targets for gestational diabetes compared to non-pregnant blood sugar goals. Your body is literally OBSESSED with keeping your blood sugar as low as possible in pregnancy.
A research study that explored patterns of glycemia in normal pregnancy across 11 studies published between 1975 and 2008 found:
“The most compelling finding from our review of the available literature is that glucose concentrations during normal pregnancy in the absence of obesity are lower than the current suggested normal therapeutic targets. [T]he weighted mean pattern of glycemia reveals an FBG of 71 ± 8 mg/dL, followed by 1- and 2-h PP glucose concentrations of 109 ± 13 and 99 ± 10 mg/dL, respectively, and a 24-h glucose of 88 ± 10 mg/dL. These weighted mean values are appreciably lower than the currently recommended therapeutic targets…” (Diabetes Care, 2011)
Myth #2: Mildly Elevated Blood Sugar is Nothing to Worry About
What if your blood sugar is only slightly elevated, by around 5-10mg/dl above targets? Certainly that’s not a problem, right? I wish that was the case, but researchers have observed that some of the problems associated with gestational diabetes can occur even in fairly “mild” cases, like having a baby with high insulin levels or one who is abnormally large at birth.
The landmark Hyperglycemia and Adverse Pregnancy Outcomes study (HAPO), which studied 23,316 women with gestational diabetes and their infants, found that even mildly elevated fasting blood sugar levels were linked to high insulin levels in infants at birth and macrosomia (Int J Gynaecol Obstet. 2002).
For example, women with an average fasting blood sugar of 90mg/dl or less had a large baby 10% of the time, compared to 25-35% in women whose average fasting blood sugar was 100mg/dl or higher. A more recent study out of Stanford found a significantly higher risk of congenital heart defects in babies born to women with mildly elevated blood sugar (even below the diagnostic criteria for gestational diabetes). (JAMA Pediatrics, 2015)
The bottom line is: your blood sugar levels in pregnancy matter. Clearly, the adverse “fetal programming” typically attributed to gestational diabetes may be occurring to mothers who experience only slightly elevated blood sugar. This means what you eat matters, the amount (and quality) of carbohydrates you eat matters, the amount of sugar you eat matters, the amount of nutrients that naturally regulate blood sugar matters, the amount of sleep you get matters, the amount of exercise you get matters, etc, etc, etc.
If your blood sugar is elevated, it means you need to get curious about why and how to fix it (meaning using food, exercise, possibly supplements and other lifestyle tweaks… and if those aren’t enough, medication or insulin). I walk you through the basics in this free 3-part video series if you’re interested to learn more.
Myth #3: Gestational Diabetes Magically Appears Out of Nowhere at the End of Pregnancy
While it’s true that insulin resistance rises in the second half of pregnancy (as a normal adaptation, so your body can shunt as many nutrients to your rapidly growing baby), gestational diabetes is rarely something that just “appears” with no warning signs.
As research into gestational diabetes has advanced, researchers noticed that rates were rising right alongside higher rates of prediabetes and type 2 diabetes in the general population. This led some to believe that gestational diabetes wasn’t entirely a phenomenon of placental hormones and pregnancy-induced insulin resistance, but undiagnosed prediabetes that was “unmasked” (meaning finally tested for) during pregnancy.
One study that measured average blood sugar in early pregnancy via a test called hemoglobin A1c (or just A1c for short), found that an elevated first trimester A1c was 98.4% specific for detecting gestational diabetes. (Diabetes Care. 2014) Coincidence? The first trimester is before the onset of insulin resistance and when blood sugar levels in pregnancy are typically lowest.
Another study found an early pregnancy A1c of 5.9% or higher is linked to a 3-fold higher rate of macrosomia (large baby) and preeclampsia. (J Clin Endocrinol Metab, 2016) Some researchers are calling for universal screening by this method, as it’s both accurate and non-invasive (and A1c can simply be added to your routine early pregnancy blood panel). Plus, if you identify a problem now, you can actually be proactive and DO SOMETHING about it, rather than just wait around until the 24-28 week glucola screening.
PS – In-the-know docs will test your first trimester A1c as an alternate way to screen for GD. Anything in the prediabetic range (5.7% or above) is considered gestational diabetes. You can also request your doctor check your A1c if it’s not on their radar. That’s what I did.
Myth #4: The Glucola/Glucose Test is Fail Safe: If You Pass the Glucose Test, You Can Eat Whatever You Want.
There’s a lot of black and white thinking when it comes to gestational diabetes. You might think that as long as you pass your GD screening test you are fine and can eat whatever you want. (I know a fair number of women who will go out for a celebration milkshake when they pass.) On the other hand, if you fail, suddenly the sky is falling! Now you’re “high risk”, will have to be on insulin, will have a large baby that will get stuck during delivery, and then you’ll be induced or need a C-section, etc, etc.
And – full disclosure – I entirely understand these fears, especially that your birthing options could be limited because of a label. If your healthcare providers fall into this fear-based thinking and have never seen gestational diabetes well-managed, they don’t always understand that there can be another way and they immediately go to worst case scenario.
It’s important to understand that blood sugar is on a continuum and the relative risk of complications relies on your blood sugar levels, not a label!
Plus, the glucose tolerance test (aka the glucola) is not perfect. Some women with an elevated first trimester A1c, indicating prediabetes, will pass the glucola despite clear blood sugar problems (false negative) (Aust N Z J Obstet Gynaecol, 2014).
Others will fail the glucola despite normal blood sugar metabolism, but as a result of eating a healthy, lower-carb diet (false positive). I described the pros and cons of different testing methods in this post (and my own personal experience of failing the 50-gram glucola screen).
Myth #5: I’m Thin. I Can’t Possibly Have Gestational Diabetes!
Screening for gestational diabetes might seem like another unnecessary test, especially if you’re otherwise healthy, but that doesn’t mean you’re in the clear. Some studies have shown up to 50% of women with gestational diabetes don’t have any of the classic risk factors, like being overweight prior to becoming pregnant or a family history of diabetes.
While the screening tests aren’t perfect (see above point), it’s still worth being proactive given all that we know about mildly elevated blood sugar levels and risks to your baby. Even if you’re not interested in the glucose drink, at the very least, using a glucometer to measure your blood sugar levels for a few weeks while you eat your usual diet teaches you a TON about food and your body. And if you’re reading this in early pregnancy, ask to have an A1c added to your blood work.
Myth #6: Diet Doesn’t Matter or Change the Risk for Gestational Diabetes
Eh, sort of. Sometimes gestational diabetes is out of your control. And sometimes there are things you can do modify these risks. If you already have a positive diagnosis, do not beat yourself up. You can’t rewind the clock to lose weight preconception or change your family medical history and the important thing is to focus on what’s in your control: how you eat and care for your body (and baby) NOW.
With that disclaimer out of the way, studies are showing that what you eat can lessen the risk of gestational diabetes, at least for some women.
Your pancreas, the organ that produces insulin, undergoes dramatic changes in pregnancy as it prepares to pump out at least triple the amount of insulin (this is to overcome the innate insulin resistance of late pregnancy and to keep your blood sugar in that nice 20% lower than usual zone). In order to do this, the pancreas needs enough of certain amino acids, suggesting that inadequate protein consumption during the first trimester is a risk factor for gestational diabetes. (Nat Med. 2010)
Another study found higher rates of gestational diabetes among women who ate more cereal, cookies, pastries, and drank juice, while lower rates were found in women who regularly ate nuts (Clinical Nutrition, 2016). Simply eating more than your body needs is a risk factor, given that excess weight gain, especially in the first trimester, ups the odds that you’ll get gestational diabetes. (Obstet Gynecol, 2011) Overconsumption of high-glycemic carbohydrates, in particular, is consistently linked to excess weight gain.
“Altering the type of carbohydrate eaten (high- v. low-glycaemic sources) changes postprandial glucose and insulin responses in both pregnant and non-pregnant women, and a consistent change in the type of carbohydrate eaten during pregnancy influences both the rate of feto–placental growth and maternal weight gain. Eating primarily high-glycaemic carbohydrate results in feto–placental overgrowth and excessive maternal weight gain, while intake of low- glycaemic carbohydrate produces infants with birth weights between the 25th and the 50th percentile and normal maternal weight gain.” (Proceedings of the Nutrition Society, 2002)
This might surprise you, but excessive fruit intake in pregnancy is linked to higher odds of gestational diabetes, especially high glycemic fruit (more is not always better when it comes to fruit).
“An increase in total fruit consumption during the second trimester was associated with an elevated likelihood of GDM (highest vs. lowest quartile: crude OR, 3.20; 95% CI, 1.83 to 5.60). After adjustment for age, education, occupation, income level, pre-pregnancy BMI, gestational weight gain, family history of diabetes, smoking status and alcohol use in Model 1, a significantly higher likelihood of GDM was still observed in the third and fourth quartiles for total fruit consumption (OR 2.81; 95% CI 1.47 to 5.36; OR 3.47; 95% CI 1.78 to 6.36, respectively).”
(Scientific Reviews, 2017)
Myth #7: All Women with Gestational Diabetes Will Have Big Babies
Not so fast… One of the big fears associated with gestational diabetes is the risk of having a large baby (also called macrosomia). Statistically it’s true. As a whole, we see more macrosomic babies among women with gestational diabetes. However you don’t have to be a statistic. The chances of having a large baby correlates very strongly to blood sugar control during pregnancy. (Int J Gynaecol Obstet. 2002)
So if you know what to do to keep your blood sugar under control, your risk of having a big baby goes way, way, way down. And if your blood sugar stays at pretty much normal levels, you are at no higher risk than a women without an “official” gestational diabetes (and probably a way lower risk than someone who had a false negative on their glucose screening and is eating whatever they want without any consideration for their blood sugar).
I have yet to have a participant in my online Real Food for Gestational Diabetes Course have a macrosomic baby. Take that, statistics.
Myth #8: Cut Back on Carbohydrates, BUT Not Less Than 175g of Carbohydrates/Day
The conventional nutrition advice for gestational diabetes is mind-numbingly nonsensical. You’re given the diagnosis of GD, aka “carbohydrate intolerance,” yet told to eat a bunch of carbohydrates. You fail a 50 or 75 gram glucose tolerance test, yet are told to eat 45-60 grams of carbohydrates (which turn into glucose in your body) at almost EVERY MEAL. It’s no wonder roughly 40% of women will require insulin and/or medication to lower their blood sugar when they’re consistently filling up their carbohydrate-intolerant body with lots of carbohydrates.
Perhaps not-so-shocking is that researchers have shown that eating a lower-glycemic diet reduces the chance a women will require insulin by HALF. (Diabetes Care, 2009) It’s common sense, friends.
Unfortunately, there’s oodles of misinformation low-carb diets. Women are warned not to eat low-carb because they might go into ketosis (even though virtually every pregnant women is in and out of ketosis on a regular basis). Plus, there’s entirely no acknowledgement that ketosis can exist outside of diabetic ketoacidosis. Sadly, few healthcare professionals have fully investigated the details and continue to fear-monger based on false information.
I’m one of the few that has done the research and I’m the first dietitian to scientifically defend the safety (and benefits) of a lower-carbohydrate diet to manage gestational diabetes (see Chapter 11 of my book, Real Food for Gestational Diabetes if you want the research-y breakdown).
I’ve also spoken at conferences on The Carbohydrate and Pregnancy Controversy, and I highly recommend you give my lecture a listen if you are curious about the research on low-carb diets, ketosis, and pregnancy. Watch it here on Vimeo.
Myth #9: You’ll Need Insulin No Matter What
That’s simply not true. The first step to managing your blood sugar is food and lifestyle tweaks, not insulin.
Now, if your healthcare provider is only familiar with conventional, high-carbohydrate diet therapy, they probably end up prescribing insulin or blood sugar lowering medication a lot. But, again, you do not automatically get put on insulin and you have the option to make more informed dietary choices to reduce your chances of needing it in the first place.
Don’t get me wrong, insulin can be an amazing tool, and, in some cases, it is needed. But, if your pancreas is still producing insulin (it’s usually producing a LOT during pregnancy) and if you can make changes to lessen your blood sugar spikes (easing the insulin demand from your already over-worked pancreas) and reduce your insulin resistance (like changing your diet and moving your body more, etc), your chances of needing insulin shots goes down.
By the way, if high fasting blood sugar is what you’re struggling with, I have an entire advanced training on lowering fasting blood sugar naturally in my online Real Food for Gestational Diabetes Course.
Whew, that was a lot and I feel like I’m just getting started. There are so, so many gestational diabetes myths and I’m passionate about helping you sort through the nonsense, the science, (and the non-science?).
I’d love to hear your thoughts on this post in the comments below. Which myth surprised you the most? Are there any other things you’ve heard about gestational diabetes that you’re not sure about? Leave me a note in the comments below, so I can address them in a future blog post.
Until next week,
PS – Wanna learn the science behind low-carb diets during pregnancy and do some myth-busting on ketosis and pregnancy? Check out my training over on Vimeo, based on my uber popular presentation at Paleo f(x) 2016, The Carbohydrate & Pregnancy Controversy: How Conventional Recommendations Stack Up Against the Evidence.
PS – If you were just diagnosed with gestational diabetes and want to learn how to manage it with real food (and lessen your chances of requiring insulin), be sure to check out my FREE video series on the topic. You’ll get 3 in-depth videos + a guide to managing your blood sugar at absolutely no cost to you. Sign up HERE or via the box below.