Gestational Diabetes Explained

Gestational diabetes is a type of diabetes that develops during pregnancy when a mother’s blood sugar, or blood glucose, is higher than it should be. In the United States, gestational diabetes occurs in approximately 2% to 10% of pregnancies.

“In pregnancy the placenta releases hormones, and their express purpose is to raise your blood sugars, because glucose is the main source of energy for the baby to grow and develop,” explains Dr. Noelia Zork, a maternal-fetal medicine expert at NewYork-Presbyterian/Columbia University Irving Medical Center. “Your body is doing this on purpose when you’re pregnant. But for some people, the blood sugars increase too much. This can lead to gestational diabetes.”

Health Matters spoke with Dr. Zork, who is also an assistant professor of Obstetrics and Gynecology at Columbia University Vagelos College of Physicians and Surgeons, about what people need to know about gestational diabetes — who is most at risk, how it is treated, and what you can do to prevent it.

According to Dr. Zork, all pregnant people are at risk of developing gestational diabetes. “A lot of it has to do with hormones coming from the placenta,” she says. “And because of genetics or personal health issues, some people are more sensitive to those hormones than other people.”

Still, there are several risk factors to be aware of. Your chance of developing gestational diabetes increases if you:

• Are older than 25
• Have a family history of diabetes
• Are pregnant with twins or triplets
• Have prediabetes
• Have had a previous baby who weighed 9 pounds or more at birth
• Are overweight (have a body mass index of 25 or higher)
• Have polycystic ovary syndrome (PCOS), a hormonal disorder that makes the body insulin-resistant

“Interestingly, around 40% of people who have gestational diabetes have zero risk factors, which is why we test everybody, because any woman who is pregnant is at risk of developing gestational diabetes,” says Dr. Zork.

Because gestational diabetes usually develops around the 24th week of pregnancy, a glucose screening test (also called the glucose challenge test) is given between 24 and 28 weeks to measure how well your body handles glucose. In this test, your blood is drawn one hour after drinking a very sweet liquid containing glucose. If that number is 135 or higher, you could have gestational diabetes.

In the U.S., that screening test is followed up with a three-hour glucose tolerance test. This diagnostic test measures your fasting blood sugar — your blood sugar on an empty stomach — as well as your blood sugar one hour after drinking the sweet liquid, then two hours later, and again at three hours. “Two abnormal levels indicate gestational diabetes,” explains Dr. Zork.

If it is not treated, gestational diabetes can cause complications for both mothers and babies. Mothers face the risk of C-section, preeclampsia, or high blood pressure in pregnancy, and developing type 2 diabetes later in life. Babies might weigh too much (which can make moving through the birth canal difficult), experience breathing problems, and have low blood glucose — hypoglycemia — right after birth.

Once someone develops gestational diabetes, there are several steps to managing it effectively.

1. Check your blood sugar regularly. “We recommend patients check their blood sugar four times a day,” says Dr. Zork. “First thing in the morning before you’ve eaten, which is your fasting blood sugar. Then one or two hours after the first bite of each meal — breakfast, lunch, and dinner.”
2. Improve your diet. Healthy food choices are vital when managing gestational diabetes. Dr. Zork recommends balancing each meal with lean protein and healthy, complex carbohydrates like whole wheat bread, brown rice, vegetables, and lots of fiber. “This pattern of eating helps to keep blood sugars in a normal and steady state.”

3. Exercise regularly. Twenty to 30 minutes, five or six times a week — can be very helpful. “Even simple exercises like marching in place for 10 minutes after your meals can actually make a huge difference in glucose control,” says Dr. Zork. “You don’t have to do it all at once. Small spurts of exercise can really add up.”
4. Get better sleep. Practice good sleep hygiene: Go to bed at the same time each night, minimize screen time right before bed, and make sure the bedroom is completely dark while sleeping. White noise can help block sounds that can disturb your sleep. “If you’re not sleeping well, blood sugars tend to increase.”
5. Lower stress levels. Managing anxiety and stress can help reduce cortisol, the stress hormone, and improve glucose levels.

From 70% to 80% of people are able to manage their gestational diabetes with diet and exercise. But for some people, even if they are eating a really healthy diet and exercising every day, sometimes their blood sugars are still high and they need medication like metformin or insulin injections. “It varies case by case,” says Dr. Zork.

Patients should not blame themselves, though. “Sometimes it’s just the luck of the draw. It’s hard to counteract all the hormonal changes that occur with pregnancy. It does not mean you’re a bad mom and it does not mean that you did something wrong.”

The Mothers Center at NewYork-Presbyterian/Columbia provides patients with resources and tools to manage their gestational diabetes. “We have a team of people that provide a lot of support to women with this diagnosis to give them the resources that they need to help manage their blood sugar so they can have a successful pregnancy in the end.”

Once you deliver and the placenta leaves your body, blood sugars usually improve dramatically. “Even people who were on very high doses of insulin prior to delivery often do not need medication anymore,” says Dr. Zork. “For the vast majority of patients with gestational diabetes, those numbers go back to being normal after delivering their baby.” Dr. Zork recommends patients get another glucose test at about six weeks postpartum to make sure blood sugar levels are back to normal.

While gestational diabetes typically goes away after pregnancy, the risk of its recurring in subsequent pregnancies is about 40%, and there is still a long-term risk for type 2 diabetes. “You don’t have to monitor your blood sugars quite as intensely, but it is important to be mindful — eating well and exercising regularly — and get screened for type 2 diabetes at least every three years with your primary care provider,” says Dr. Zork.

When it comes to prevention, these three tips can lower your chances of developing gestational diabetes:

1. Stay at a healthy weight. If you are thinking about becoming pregnant and are overweight, you can lower your chance of developing gestational diabetes by losing extra weight and increasing physical activity before you become pregnant.
2. Stay within your weight goals during pregnancy. “Women who gain too much weight too early in their pregnancy are at increased risk of gestational diabetes,” says Dr. Zork.
3. Exercise regularly. Exercise in pregnancy has been shown to lower a woman’s risk of developing gestational diabetes.

“I like to reassure patients that the things that are learned during pregnancy can continue to help you afterward,” says Dr. Zork. “With attention and care, you can definitely manage gestational diabetes and have a healthy pregnancy and baby.”

Noelia M. Zork, M.D., is a maternal-fetal medicine specialist at NewYork-Presbyterian/Columbia University Irving Medical Center and an assistant professor of Obstetrics and Gynecology at Columbia University Vagelos College of Physicians and Surgeons. In addition to prenatal diagnosis and ultrasound, Dr. Zork’s clinical interests include diabetes in pregnancy, obesity and nutrition in pregnancy, preterm labor, and cervical insufficiency.