Diabetes that develops during pregnancy is called gestational diabetes, or by its full medical name, gestational diabetes mellitus (often abbreviated GDM). It’s a type of diabetes that first appears during pregnancy in women who didn’t have diabetes before conceiving. In the United States, roughly 8 out of every 100 live births are now affected, and that rate has been climbing steadily since 2016.
What Gestational Diabetes Actually Is
Gestational diabetes is not the same as having type 1 or type 2 diabetes while pregnant. It develops because of changes your body goes through specifically during pregnancy. Your placenta produces hormones that help your baby grow, but those same hormones make your cells less responsive to insulin, the hormone that moves sugar out of your blood and into your cells for energy.
Some degree of insulin resistance during pregnancy is normal and even helpful: it keeps extra glucose available in your bloodstream so your baby can use it for growth. But when your pancreas can’t produce enough extra insulin to overcome that resistance, blood sugar levels stay too high, and that’s gestational diabetes. Recent research from the National Institute of Child Health and Human Development has identified specific molecules released by the placenta that regulate this process, helping explain why some women develop the condition and others don’t.
Who Is Most Likely to Develop It
Several factors raise your chances of gestational diabetes:
- Previous gestational diabetes in an earlier pregnancy
- A prior baby weighing over 9 pounds at birth
- Being overweight before pregnancy
- Family history of type 2 diabetes
- Polycystic ovary syndrome (PCOS)
- Certain racial and ethnic backgrounds, including African American, Hispanic or Latino, American Indian, Alaska Native, Native Hawaiian, and Pacific Islander
Having one or more of these risk factors doesn’t mean you’ll definitely develop gestational diabetes, but it does mean your provider may screen you earlier in pregnancy than usual.
How and When It’s Diagnosed
Most women are screened between 24 and 28 weeks of pregnancy, during the second trimester. If you have high-risk factors, your provider may test earlier. There are two common approaches to screening.
In the two-step method, you first drink a sugary solution containing 50 grams of glucose without needing to fast beforehand. Your blood sugar is checked one hour later. If it’s at or above 130 to 140 mg/dL (the exact cutoff varies by practice), you move on to a longer follow-up test where you fast overnight, drink a larger glucose solution, and have your blood drawn multiple times over several hours.
In the one-step method, you fast beforehand, drink a 75-gram glucose solution, and have your blood sugar measured at one hour and two hours. A single reading at or above the threshold is enough for a diagnosis. Both approaches are widely used, and your provider will choose one based on their clinical preference and guidelines.
Risks for You and Your Baby
When blood sugar stays too high during pregnancy, it can cause problems for both mother and baby. Excess glucose crosses the placenta and reaches your baby, who then produces extra insulin to handle it. That extra energy gets stored as fat, which can lead to a larger-than-average baby. A bigger baby increases the likelihood of a difficult delivery and raises the chance you’ll need a cesarean section.
For you, gestational diabetes increases the risk of high blood pressure complications during pregnancy. It also raises your odds of developing type 2 diabetes later in life. Your baby may also face a higher risk of obesity and type 2 diabetes as they grow up. The good news is that managing your blood sugar effectively during pregnancy significantly reduces all of these risks.
How It’s Managed Day to Day
The first line of treatment is dietary changes and physical activity, and for many women, that’s enough to keep blood sugar in a healthy range. The core dietary strategy is keeping your carbohydrate intake consistent and choosing complex carbohydrates (whole grains, beans, vegetables) over simple ones like white rice, potatoes, candy, and soda. Less than half your daily calories should come from carbohydrates.
Eating three small to moderate meals plus one or more snacks each day, rather than skipping meals or eating large portions, helps prevent blood sugar spikes and drops. Keeping the types and amounts of food roughly similar from day to day also makes blood sugar more predictable. A typical daily pattern includes plenty of vegetables (3 to 5 servings), fruit (2 to 4 servings), whole grains and starchy vegetables (6 or more servings), low-fat dairy (4 servings), and protein like meat, fish, eggs, or beans (2 to 3 servings).
Walking is the most commonly recommended exercise because it’s accessible and low-impact, but swimming and similar activities work just as well. Regular movement helps your body use insulin more efficiently. You’ll also check your blood sugar at home, typically several times a day, so you and your provider can see how well your plan is working. If diet and exercise aren’t enough to control blood sugar, insulin or other medications may be added.
What Happens After Delivery
For most women, blood sugar returns to normal shortly after giving birth once the placenta is delivered and those pregnancy hormones drop. But having gestational diabetes is a strong signal that your body is prone to insulin resistance, which means your risk of developing type 2 diabetes remains elevated for years afterward.
The American Diabetes Association recommends a glucose tolerance test 6 to 12 weeks after delivery, then again at one year postpartum. After that, periodic screening every one to three years is typical. Maintaining a healthy weight, staying physically active, and eating well after pregnancy are the most effective ways to reduce your long-term risk. If you had gestational diabetes in one pregnancy, you’re also more likely to develop it again in future pregnancies, so early screening in subsequent pregnancies is standard.