Gestational Diabetes
High blood sugar that develops during pregnancy in someone who did not have diabetes before.
Last revised
Key takeaways
- Usual screening time: 24 to 28 weeks of pregnancy
- ADA glucose targets in pregnancy: fasting under 95 mg/dL; under 140 mg/dL one hour or under 120 mg/dL two hours after meals, unless your team sets others
- Most useful single change: Follow the eating plan your care team or a registered dietitian gives you, spreading carbohydrates through the day.
- Commonest mistake: Skipping meals to keep numbers down, which can cause low blood sugar.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Unmanaged, it raises the chance of a large baby, a cesarean birth, low blood sugar in the newborn and high blood pressure in pregnancy, and it signals a higher risk of type 2 diabetes later in life.
The numbers, in one place
| Measure | Figure |
|---|---|
| Usual screening time | 24 to 28 weeks of pregnancy |
| ADA glucose targets in pregnancy | fasting under 95 mg/dL; under 140 mg/dL one hour or under 120 mg/dL two hours after meals, unless your team sets others |
| Testing after birth | a glucose test at 4 to 12 weeks postpartum |
| Long-term follow-up | diabetes screening at least every 3 years |
| Later type 2 diabetes | about half of people with gestational diabetes go on to develop it, per CDC |
What helps
- Follow the eating plan your care team or a registered dietitian gives you, spreading carbohydrates through the day
- Check your blood sugar as often as you are asked and bring your log to visits
- Walk or stay active most days if your provider agrees; activity after meals can help lower blood sugar
- Take insulin or other medicines exactly as prescribed if diet and activity are not enough
- Keep your postpartum glucose test appointment and tell future doctors you had gestational diabetes
What to avoid
- Skipping meals to keep numbers down, which can cause low blood sugar
- Sugary drinks and juice, which raise blood sugar quickly
- Assuming the risk is over once the baby is born
In depth
In the second half of pregnancy, the placenta releases hormones that make the body less responsive to insulin. This is normal and helps keep more glucose available for the baby. Most people make extra insulin to compensate. Gestational diabetes develops when the pancreas cannot keep up with this extra demand, and blood sugar rises above the target range.
Glucose crosses the placenta easily, but insulin does not. When the parent's blood sugar is high, the baby receives extra glucose and makes more insulin of its own, which acts like a growth hormone. This is why gestational diabetes can lead to a large baby, a harder birth, and low blood sugar in the newborn shortly after delivery, when the extra supply suddenly stops.
For most people, blood sugar returns to normal soon after birth because the placenta is gone. But the diagnosis reveals that the body was already under strain, and the risk of type 2 diabetes in later years is much higher. Gestational diabetes is best seen as an early warning that gives you time to act, not just a pregnancy problem that ends at delivery.
Signs and symptoms
- Usually no symptoms at all, which is why everyone is screened
- Increased thirst or needing to urinate more than usual, though both are common in pregnancy anyway
- Tiredness beyond the usual tiredness of pregnancy
- A baby measuring larger than expected or extra amniotic fluid on ultrasound
- Sugar found in a routine urine check
Causes and risk factors
- Placental hormones that increase insulin resistance in later pregnancy
- Overweight or obesity before pregnancy
- Gestational diabetes in a previous pregnancy or a previous large baby
- A family history of type 2 diabetes
- Polycystic ovary syndrome (PCOS) or prediabetes
- Being of African American, Hispanic or Latino, American Indian, Alaska Native, Asian American or Pacific Islander descent, groups with higher rates
How it is checked
Most US practices use a two-step approach. First comes a glucose challenge test: you drink a sugary solution and have blood drawn an hour later, without needing to fast. If the result is above a cutoff, you return for a longer fasting test with several blood draws over a few hours. Some practices use a single fasting two-hour test instead.
People with risk factors are often tested earlier in pregnancy, sometimes at the first visit, to look for diabetes that was present but undiagnosed before pregnancy. An HbA1c test may be used at that early stage. After diagnosis, home blood sugar checks, usually fasting and after meals, show how well the eating plan and activity are working.
Related topics
- Type 2 Diabetes: Sorting the Evidence From the Noise (Diabetes)
- What the Guidance Really Says About Vaccination in Pregnancy (Vaccinations)
- Listeria in Pregnancy: What Published Guidance Supports (Food Safety)
- What the Guidance Really Says About Diabetes and the Kidneys (Kidney Health)
Where to go next
- Gestational Diabetes for Beginners: Where to Start
- A Q and A on Gestational Diabetes
- Pregnancy and Postpartum: The Complete Guide
- What the Guidance Really Says About Preeclampsia Warning Signs
- Vaccines During Pregnancy: What the Evidence Actually Says
When to get help
Call your care team if your readings stay above your targets, or if you are very thirsty, urinating much more than usual or feel shaky and sweaty. Call 911 if you become confused, cannot stay awake, have a seizure or are unable to treat a low blood sugar.
Where this comes from
- CDC — Gestational Diabetes
- American Diabetes Association — Standards of Care in Diabetes
- National Institute of Diabetes and Digestive and Kidney Diseases — Gestational Diabetes
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.