Gestational diabetes means your body can’t make enough insulin to keep your blood sugar in a normal range during pregnancy. It develops in the second or third trimester, even in people who never had blood sugar problems before, and it affects roughly 2% to 10% of pregnancies in the United States each year. The good news: with proper management, most people with gestational diabetes have healthy pregnancies and healthy babies.
Why It Happens During Pregnancy
As your placenta grows, it releases hormones that help your baby develop. Those same hormones make your cells less responsive to insulin, the hormone that moves sugar from your blood into your cells for energy. Every pregnant person experiences some degree of this insulin resistance, especially in the second half of pregnancy. Your pancreas normally compensates by producing more insulin. Gestational diabetes develops when your pancreas can’t keep up with the extra demand.
This isn’t caused by eating too much sugar. Certain factors raise your risk: being overweight before pregnancy, having a family history of type 2 diabetes, being over 25, or having had gestational diabetes in a previous pregnancy. But plenty of people with no obvious risk factors get diagnosed too.
Most People Have No Symptoms
Gestational diabetes rarely causes noticeable symptoms. You might feel more thirsty than usual or need to urinate more often, but those overlap so heavily with normal pregnancy that they’re easy to miss. That’s why screening is routine. Most providers test between 24 and 28 weeks of pregnancy using a glucose tolerance test, where you drink a sugary solution and have your blood drawn afterward to see how your body handles the sugar load.
In the most common two-step approach, you first take a one-hour screening test. If your blood sugar comes back high, you return for a longer three-hour test. On that follow-up test, you’re diagnosed with gestational diabetes if two or more of your readings exceed specific thresholds: a fasting level above 95 mg/dL, a one-hour reading above 180 mg/dL, a two-hour reading above 155 mg/dL, or a three-hour reading above 140 mg/dL.
What It Means for Your Baby
When your blood sugar runs high, extra glucose crosses the placenta and reaches your baby. Your baby’s pancreas responds by producing more insulin, and that extra insulin acts like a growth hormone. The result can be a condition called macrosomia, where the baby weighs more than 8 pounds, 13 ounces at birth. Babies with macrosomia tend to develop larger shoulders and more body fat, which can make vaginal delivery more difficult and increase the chance of a cesarean section.
High blood sugar during pregnancy also raises the risk of your baby having low blood sugar right after birth, since their body has been producing extra insulin throughout the pregnancy and suddenly loses the supply of glucose from your bloodstream. Babies born to mothers with poorly managed gestational diabetes are also more likely to be born preterm or to need time in the neonatal intensive care unit. All of these risks drop significantly when blood sugar is well controlled.
What It Means for You
Gestational diabetes increases your risk of developing preeclampsia, a dangerous condition involving high blood pressure during pregnancy. In one large study, about 10% of people with gestational diabetes developed preeclampsia. That rate climbed to nearly 14% in those with higher fasting blood sugar levels and reached 18% in those with both high fasting glucose and poor overall blood sugar control. Pre-pregnancy weight and the severity of gestational diabetes were the two strongest independent predictors of preeclampsia risk.
The longer-term concern is type 2 diabetes. About half of people who have gestational diabetes eventually develop type 2 diabetes later in life. That number sounds alarming, but it’s spread over many years, and lifestyle changes after pregnancy can meaningfully lower that risk.
How Blood Sugar Is Managed
The first line of treatment is changing what and how you eat, combined with regular physical activity like walking after meals. The goal is to keep your fasting blood sugar below 95 mg/dL and your blood sugar one to two hours after meals at 120 to 140 mg/dL or lower. You’ll check your blood sugar several times a day using a finger-stick glucose monitor to see how different foods and portions affect your numbers.
There’s no single prescribed carbohydrate limit that works for everyone. Instead, most people learn to spread carbohydrates evenly across meals and snacks rather than eating a large amount at once. Pairing carbohydrates with protein, fat, or fiber slows digestion and prevents sharp blood sugar spikes. A dietitian or diabetes educator can help you build a meal plan that keeps your levels steady without leaving you hungry.
For many people, diet and activity changes are enough. But if your blood sugar exceeds targets more than about a third of the time over the course of a week, your provider will recommend medication. When fasting blood sugar is moderately elevated (between 95 and 126 mg/dL), metformin, taken as a pill, is typically offered first. It’s associated with less weight gain during pregnancy and a lower chance of pregnancy-related high blood pressure compared to insulin. If metformin alone doesn’t bring numbers into range within one to two weeks, insulin injections are added. When fasting levels are above 126 mg/dL, insulin is usually the first choice because more aggressive blood sugar control is needed.
What Happens After Delivery
Gestational diabetes almost always resolves once the placenta is delivered, because the hormones driving insulin resistance drop quickly. Most people can stop checking their blood sugar and stop any medication shortly after birth. But the story doesn’t end there.
Guidelines recommend a follow-up glucose tolerance test between 6 weeks and 6 months after delivery to make sure your blood sugar has returned to normal. This matters more than a simple fasting blood sugar check. A fasting test alone can miss up to 40% of ongoing blood sugar problems, so the full oral glucose tolerance test, where you drink a glucose solution and have blood drawn at intervals, gives a much more accurate picture.
If your postpartum results come back normal, you should still have your blood sugar checked every one to three years going forward, given the elevated lifetime risk of type 2 diabetes. Maintaining a healthy weight, staying physically active, and eating a balanced diet are the most effective ways to reduce that risk over time. Breastfeeding may also help by improving insulin sensitivity in the months after delivery.
What a Diagnosis Doesn’t Mean
A gestational diabetes diagnosis does not mean you did something wrong during pregnancy, that you’ll need insulin, or that your baby will have diabetes. It means your body’s insulin production couldn’t quite keep pace with the demands of pregnancy, something largely determined by genetics and placental hormones outside your control. Most people manage it successfully with dietary adjustments alone, carry to term, and deliver healthy babies. The key is consistent blood sugar monitoring and staying in close contact with your care team so adjustments can be made quickly if needed.