When you’re pregnant, you want to do everything you can to ensure your baby is a healthy as possible. So, you give up alcohol, get regular checkups, and never miss a day of taking your prenatal vitamins.
But how much attention are you paying to your blood sugar? A recent study published in BJOG: International Journal of Obstetrics and Gynaecology is putting a laser focus on the serious risks of elevated blood sugar during pregnancy and what moms-to-be need to know to stay healthy.
Specifically, the study found that if you’re pregnant and have risk factors for gestational diabetes mellitus (GDM)—but you are not screened, diagnosed, or treated for it—you have up to a 44% increased risk of stillbirth.
While these findings can be frightening, there is good news, too. Screening is routine for all women between 24 and 28 weeks of pregnancy, and those who are at increased risk can--and should--be screened sooner. Because when high blood sugar is caught and treated, you can greatly reduce the chance for potential danger, according to the study. That’s the key: You’ll need to be an informed and proactive mother-to-be (we bet you already are), get proper screening and treatment for GDM when needed, and have a partnership with a knowledgeable health care provider throughout your pregnancy.
We tapped two top experts on GDM to get you started on the right path: endocrinologist Louis H. Philipson, M.D., Ph.D., president of medicine and science for the American Diabetes Association (ADA), and endocrinologist Laura Dickens, M.D., both of the University of Chicago Medical Center’s Kovlar Diabetes Center. Get the facts you need, then follow their five steps for managing your risk for GDM.
Blood Sugar and Gestational Diabetes: The Facts
First, let's get a handle on what this often-confusing condition even is. Blood sugar (or glucose) comes from the food you eat and supplies energy to your body. Insulin, a hormone made by your pancreas, has the job of directing that glucose out of your bloodstream and into your cells.
During pregnancy, it’s common for your cells to become less responsive to the insulin you produce, a condition called insulin resistance. As a result, your blood-sugar levels can rise. In as many as 1 in 10 women, according to the Centers for Disease Control, they become so elevated that gestational diabetes develops. The main difference between GDM and other types of diabetes? It typically resolves after delivery. While sometimes GDM causes no noticeable symptoms, some women experience the following:
- Feeling especially thirsty
- Rapid weight gain during pregnancy
- Frequent urination
- More frequent infections, especially vaginal, bladder, or skin infections
- Blurred vision
Some of these symptoms may sound like no biggie or may mimic normal pregnancy symptoms, but GDM is serious: If untreated, it can increase your risk for high blood pressure during pregnancy (including a condition called preeclampsia), and increased rates of cesarean section.
The extra glucose in your blood also crosses the placenta, causing your baby to produce too much insulin. The baby then faces increased risks, including:
- Macrosomia (the medical term for a large baby weighing 9 pounds or more)
- Premature delivery
- Low blood sugar (hypoglycemia) in your baby after birth (which can cause seizures and more serious complications)
We know this information is scary, but remember, there's a lot you can do to help ensure your pregnancy is as healthy as possible.
Step 1: Know Your Gestational Diabetes Risk Factors
One of the most important things you can do is to familiarize yourself—and make your health care providers aware of—your GDM risk factors. According to Drs. Phillipson and Dickens, the ADA Standards of Care identify the following characteristics. If you have any of them, talk to your ob/gyn:
- Being overweight or obese, with a body mass index (BMI) of 25 or higher (23 or higher in Asian Americans)
- A history of prediabetes or GDM
- A parent, sibling, or child with diabetes
- Race or ethnicity at higher risk of GDM, including African Americans, Latinas, Native Americans, Asian Americans, and Pacific Islanders
- A history of cardiovascular disease and/or hypertension
- Low HDL cholesterol levels (below 35)
- High triglyceride levels (above 250)
- A history of polycystic ovary syndrome (PCOS)
- Physical inactivity
- A skin condition known as acanthosis nigricans. (Acanthosis nigricans symptoms include discolored and dark patches in the folds and creases of your body, such as the armpits, groin, and neck.)
The American College of Obstetricians and Gynecologists (ACOG) adds another risk factor: having previously given birth to an infant with macrosomia because it's associated with high maternal blood sugar.
Other risk factors, according to the Centers for Disease Control and Prevention, include a personal history of recurrent miscarriage, fetal death, stillbirth, or neonatal death.
Step 2: Get Early Screening if You Are at Risk
“All pregnant women should be screened for GDM at 24 to 28 weeks, regardless of risk factors,” say the doctors. “With the increasing prevalence of type 2 diabetes worldwide, however, women with risk factors should be screened in early pregnancy for pre-existing diabetes.”
The ADA Standards of Care recommend that women with risk factors get tested for undiagnosed diabetes at the first prenatal visit. At that point, if you are diagnosed with diabetes, it’s considered preexisting, pre-gestational diabetes. In that case, it’s usually type 2 diabetes, and less commonly type 1.
But when diabetes is diagnosed in the second or third trimester of pregnancy and was not preexisting, it is defined as GDM, Drs. Phillipson and Dickens say.
Step 3: Don’t Rely Solely on Urine Glucose Testing
Women without risk factors for GDM typically have periodic urine glucose testing during pregnancy checkups. According to Drs. Phillipson and Dickens, if you have GDM risk factors, those urine glucose tests—along with the glucose-tolerance test during weeks 24 to 28 in your second trimester—are not enough.
“Glycosuria (high blood sugar in the urine) can be seen at some point in pregnancy in 50% of women. A random urine glucose could miss more subtle hyperglycemia,” Drs. Phillipson and Dickens explain. “Early pregnancy screening using standard diagnostic criteria—fasting plasma glucose (FPG), the oral glucose-tolerance test (OGTT), or hemoglobin A1c—should be done when women have risk factors.”
The following are the diagnostic criteria that should be used to diagnose pre-existing diabetes in the first trimester of pregnancy, per Drs. Phillipson and Dickens:
- Fasting plasma glucose above 125
- Hemoglobin A1c above 6.5%
- A 75 g oral glucose tolerance test level equal to or greater than 200
- Symptoms of high blood sugar, along with a random plasma glucose level above 200
The doctors also note that A1c can be unreliable in the second and third trimesters of pregnancy: “Physiologic changes in pregnancy cause a decrease in hemoglobin A1c, so women with higher average blood sugars could be missed. After the first trimester, screening with the oral glucose tolerance test is the best approach in most cases.”
Step 4: Make Changes to Your Diet and Lifestyle
The good news is that “a majority (80% to 90%) of mild GDM cases can be managed with diet alone,” according to Drs. Phillipson and Dickens. “Lifestyle interventions are also recommended for all women at risk for GDM, including medical nutrition therapy, physical activity, weight management, and glucose monitoring.”
The doctors caution that oral medications like metformin (Glucophage) and glyburide (Diabeta, Glynase) are not FDA-approved for use in pregnancy. Both drugs cross the placenta and lack long-term safety data for use in pregnancy.
Regarding diet, the doctors point to the Dietary Reference Intakes (DRI) for pregnant women in the ADA Standards of Care. These say that women should aim for a daily minimum of 175 g of carbohydrates, 71 g of protein, and 28 g of fiber from their food.
The doctors add: “The Endocrine Society provides more specific guidance to limit carbohydrates to 35% to 45% of total calories, distributed in three small to moderate-sized meals and two to four snacks, including an evening snack.”
And while the data is limited, some studies have shown a benefit in following a low-glycemic index diet.
Step 5: Get Proper Treatment for GDM
When diet and lifestyle interventions are not effective at lowering your blood sugar levels to target levels, insulin is the preferred therapy for gestational diabetes.
“Insulin analogues—such as insulin aspart (Novolog), insulin lispro (Humalog / U-100 and U-200), and insulin detemir (Levemir)— have been assigned an FDA pregnancy category of B, meaning they are low risk in pregnancy,” the doctors say.
Drs. Phillipson and Dickens also recommend home blood-glucose monitoring, using either a traditional glucometer for finger-stick testing, or a wearable continuous glucose monitor (CGM).
Summing It All Up
Elevated blood sugar and GDM can be dangerous during pregnancy, but thankfully, you and your doctor have all the tools to protect you and your baby. Here are the main things to keep in mind:
- Whether or not you have any gestational diabetes risk factors, get periodic glucose screening during your pregnancy, and a glucose-tolerance test between weeks 24 to 28.
- Know your risk factors for gestational diabetes, and make sure your team of health care providers is aware of those risks.
- If you have gestational diabetes risk factors, discuss them with your provider—and ensure that you have proper screening—at your first prenatal visit.
- If you have gestational diabetes risk factors or mild GDM, work with your health care providers throughout your pregnancy to manage your blood sugar levels with diet, exercise, and other lifestyle changes.
- If you are diagnosed with moderate or severe GDM, or diet and exercise aren’t managing your blood sugar levels in a healthy range, work with your doctor to follow an effective glucose monitoring and insulin treatment plan.