Gestational diabetes mellitus (GDM) occurs when people who are pregnant are unable to maintain normal glucose levels in the face of these hormonal changes that occur during normal pregnancy.

GDM is on the rise, too. According to a Northwestern Medicine study, GDM increased every year in the United States from 2016 to 2024. Over those nine years, the rate went up by 36%, climbing from 58 to 79 per 1,000 births. The increase was seen across all racial and ethnic groups.

Northwestern Medicine Endocrinologist Emily D. Szmuilowicz, MD, MS, director of the Diabetes in Pregnancy Program at Northwestern Medicine, shares what you need to know about gestational diabetes.

Testing for Gestational Diabetes

Typically, GDM causes no symptoms. However, it can cause pregnancy complications, including large babies, which can mean difficult deliveries, and risk that the children will have issues managing their blood sugar, which is why it’s important to test for it.

Your care team will generally perform routine screening for GDM at 24 to 28 weeks of pregnancy. The test involves drinking a small sugary beverage and then getting your blood drawn after one hour to see how your body responds to the increase in glucose. If your blood sugar levels are still high after this hour, your care team may recommend a second glucose test, during which you wait three hours instead of one before getting your labs drawn.

There are many well-known factors that increase your risk for developing gestational diabetes. You may be at higher risk if you:

• Have excess weight or obesity
• Are physically inactive
• Had GDM in a previous pregnancy
• Have a personal history of prediabetes
• Are more than 25 years old
• Had a very large baby (9 pounds or more) in a previous pregnancy
• Have high blood pressure, a history of heart disease or polycystic ovary syndrome (PCOS)
• Are a member of a higher-risk ethnic group
• Have a family history of diabetes, particularly in a first-degree relative
• Have a twin or multiples pregnancy (Gestational diabetes is two to three times more common in twin and multiples pregnancies, as you typically have multiple placentas or a larger placenta.)

Implications of GDM

“GDM is a quintessential example of the concept of pregnancy as a ‘window’ into a woman's future health,” says Dr. Szmuilowicz. “The metabolic stress of pregnancy enables an underlying predisposition to diabetes to become known at a young age, when a woman may be able to enact the lifestyle modifications that could stave off future disease.” As a result, the diagnosis of GDM has important implications for the long-term health of the mother.

Additionally, research has shown that the mother’s blood glucose level during pregnancy influences the future risk of both obesity and glucose intolerance in their child.

Managing Gestational Diabetes

The mainstay of treatment for GDM is medical nutrition therapy, which is “sufficient for 80% to 90% of people who are pregnant,” says Dr. Szmuilowicz. This involves making sure you are eating the recommended amount of carbohydrates and balancing them with protein and unsaturated fats.  

“We emphasize the need to pair protein with carbohydrates at meals and snacks to help blunt the after-meal carbohydrate-induced rise in glucose levels,” says Dr. Szmuilowicz.

People with gestational diabetes are advised to check glucose levels with a fasting finger prick (before breakfast), and one hour after each meal. When glucose goals are not met through nutrition therapy alone, insulin therapy is introduced and frequently adjusted based on glucose monitoring.

“Fortunately, with effective treatment, the risks of complications are reduced,” adds Dr. Szmuilowicz.

Your care team will advise you to check your glucose levels at a postpartum visit to ensure that your blood sugar levels have returned to normal.

Bottom Line

Changes throughout pregnancy are normal ― and necessary ― for your baby to grow. Your care team will screen you for GDM during pregnancy. Care for GDM is important for you and your baby not just during pregnancy, but also for your and your baby’s long-term health.

Take a diabetes risk assessment.