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Metabolic/endocrine Routine

Gestational diabetes

Also known as Gestational diabetes mellitus, GDM. Screened at 24–28 weeks.

Gestational diabetes rarely makes you feel any different, which is why nearly everyone is screened for it between 24 and 28 weeks. It is high blood sugar that first appears during pregnancy, and it is not caused by eating too much sugar or anything you did wrong. The placenta makes hormones that block insulin, and in some pregnancies the body cannot keep up. With diet, activity, and sometimes medication, it is very manageable, and blood sugar usually returns to normal after the baby is born.

Know the warning signs When to call a provider
How common
About 8% of pregnancies
Roughly 5% to 9% in the US, and rising with age.
When
Screened at 24–28 weeks
Earlier if you have risk factors.
Urgency
Routine and managed
Found on screening, not usually by symptoms.
Outlook
Very good with control
Blood sugar usually normalizes after birth.

Understanding it

What is gestational diabetes?

Gestational diabetes affects roughly 8% of pregnancies in the United States, a number climbing along with the age at which people have children. The definition is simple: blood sugar that runs too high, first recognized during pregnancy, in someone who did not have diabetes beforehand.

The cause is hormonal, not dietary. As the placenta grows, it releases hormones, chiefly human placental lactogen, that make your cells resistant to insulin, helpfully shunting fuel to your baby. Your pancreas answers with more insulin; gestational diabetes develops when it cannot make quite enough, and blood sugar rises.

Because high blood sugar rarely makes you feel sick, gestational diabetes almost never announces itself, which is the reason for the routine glucose test nearly everyone is offered. Catching it matters: your blood sugar crosses the placenta, and steadily high levels can make your baby grow large, complicate delivery, and cause low blood sugar in the newborn.

It is very treatable. Most people manage with eating and activity plus a few finger-stick checks a day; about one in five to one in three need insulin or another medication. Blood sugar typically normalizes soon after delivery, though gestational diabetes is an early flag for future diabetes, so follow-up testing matters.

Symptoms

What are the symptoms?

Gestational diabetes usually causes no noticeable symptoms and is found through routine screening rather than by how you feel. Any symptoms are the general signs of high blood sugar.

Early signs

  • Usually none
  • Increased thirst
  • Needing to urinate more often than the usual pregnancy frequency
  • Fatigue

Emergency signs — call 911

  • A noticeable decrease in your baby's movements
  • Signs of preeclampsia, which is more common with gestational diabetes: severe headache, vision changes, or sudden swelling
  • Vomiting and being unable to keep fluids down, which can lead to a dangerous state called ketoacidosis
  • If you take insulin: shakiness, sweating, confusion, or fainting from very low blood sugar

Why it matters

Risks to you and baby

A larger baby (macrosomia)

Extra blood sugar can make your baby grow large, raising the chance of a difficult delivery, shoulder dystocia (the shoulder getting stuck during birth), and a cesarean. Good control lowers this.

Newborn low blood sugar

After birth, your baby's pancreas may still be making extra insulin, causing low blood sugar (hypoglycemia) in the first hours. This is checked for and easily treated.

Preeclampsia and cesarean birth

Gestational diabetes raises your own risk of preeclampsia and makes a cesarean more likely, often because of the baby's size.

Breathing problems and jaundice

Babies of higher-blood-sugar pregnancies can have more trouble with breathing and jaundice, especially if born early.

Future diabetes, for both of you

About half of people with gestational diabetes develop type 2 diabetes later, and your child carries a somewhat higher lifetime risk. Both reward healthy habits after pregnancy.

How it's found

How is it diagnosed?

Gestational diabetes is found with a glucose test, not by symptoms. The US most often uses a two-step test, though a one-step version exists. Both are done at 24 to 28 weeks, or earlier with risk factors.

Glucose challenge test (screening step)

You drink a 50-gram glucose drink and have blood drawn an hour later, without fasting. A result at or above the cutoff (commonly 130 to 140) sends you to the longer test.

Three-hour glucose tolerance test (two-step)

After fasting, you drink a 100-gram glucose drink with blood drawn at 1, 2, and 3 hours. Two or more values above the thresholds (fasting 95, 1 hour 180, 2 hours 155, 3 hours 140) confirm the diagnosis.

Two-hour glucose tolerance test (one-step)

After fasting, a 75-gram glucose drink with blood drawn at 1 and 2 hours. A single value at or above the thresholds (fasting 92, 1 hour 180, 2 hours 153) makes the diagnosis.

Early screening

With risk factors like obesity, prior gestational diabetes, or a family history, you may be tested at your first visit to catch diabetes that predates the pregnancy.

Standard screening is at 24 to 28 weeks; higher-risk pregnancies earlier, sometimes at the first prenatal visit.

Treatment

How is it managed?

The foundation is nutrition, activity, and checking your blood sugar. Many reach their targets this way; some need medication. The goal is steady blood sugar, which protects your baby and you.

Treatment paths

Care usually starts with a meal plan (often with a dietitian), regular activity, and checking your blood sugar several times a day, fasting and after meals. Common targets are under 95 fasting and under 140 one hour after meals (or under 120 at two hours). If lifestyle cannot reach them, medication is added.

Medication

Insulin is first-line, because it does not cross the placenta and is well understood in pregnancy. Metformin is sometimes used as an alternative. Needing medication is common and no fault of yours; it reflects how strong the placenta's hormones are.

Monitoring

You will keep a blood sugar log, and your provider follows your baby's growth with ultrasounds and, near term, extra monitoring. After birth, your baby's blood sugar is checked.

Can it recur?

Yes. It recurs in roughly 40% to 70% of future pregnancies, and up to half of people develop type 2 diabetes afterward. Have a glucose test 4 to 12 weeks after delivery and screening every 1 to 3 years; staying active and at a healthy weight lowers that risk.

What you can do

Can it be prevented?

  • Enter pregnancy at a healthy weight and active

    Reaching a healthy weight before conceiving and staying active are the best-supported ways to lower the risk of gestational diabetes.

  • Keep moving during pregnancy

    Regular activity your provider approves helps your body use insulin more effectively, to prevent and to manage gestational diabetes.

  • Follow up after birth

    A postpartum glucose test and ongoing screening catch type 2 diabetes early, when lifestyle changes work best.

Who is more at risk

Risk factors

Weight and activity
Being overweight or obese, and being inactive, are among the most common risk factors.
A prior affected pregnancy
Having had gestational diabetes before, or having delivered a baby over 9 pounds (about 4.1 kg), raises the risk.
Prediabetes and PCOS
Prediabetes and polycystic ovary syndrome both involve insulin resistance and increase risk.
Family history
A parent or sibling with diabetes makes gestational diabetes more likely.
Age and ethnicity
Risk rises with age, and is higher among Black, Hispanic, American Indian, and Asian people.
About 2.7% under age 20 versus 15.6% at 40 and older

Do not wait

When to call your provider or 911

  • Seek urgent care if you are vomiting and cannot keep fluids down, which can lead to ketoacidosis, a dangerous buildup of acids.
  • Call right away if you notice your baby moving less than usual.
  • Call for signs of preeclampsia, more common here: severe headache, vision changes, or sudden swelling of the face and hands.
  • If you take insulin, treat and report very low blood sugar (shakiness, sweating, confusion); seek emergency care for fainting or a seizure.
  • Call if home readings stay above your targets despite following your plan, so treatment can be adjusted.

Talking to your team

Questions to ask your provider

  • What are my blood sugar targets, and how often should I check?
  • Can I manage with diet and activity, or am I likely to need medication?
  • Can I see a dietitian to build a meal plan?
  • How will you monitor my baby's growth and wellbeing?
  • Does this change my delivery plan or timing?
  • What blood sugar test do I need after the baby is born?
  • What can I do now to lower my chance of type 2 diabetes later?

Keep reading

More on gestational diabetes

All pregnancy guides articles

Good to Know

Gestational diabetes FAQs

Common questions about gestational diabetes, answered.

Did I cause this by eating too much sugar?

No. Gestational diabetes is driven by placental hormones that block insulin, not your diet. Plenty of people who eat well and are at a healthy weight still develop it. What you eat helps manage it, but it is not the cause.

Will my baby be born with diabetes?

No. Your baby will not have diabetes at birth. Your baby can have low blood sugar in the first hours, which is checked and treated, and carries a somewhat higher lifetime risk of obesity and diabetes, offset by healthy habits.

Will I have to take insulin?

Maybe, and it is nothing to fear. Many manage with diet and activity alone, but about one in five to one in three need insulin or another medicine to hit targets. Insulin does not cross the placenta and is the best-understood option in pregnancy.

Will it go away after I deliver?

For most people, yes. Blood sugar usually normalizes soon after birth, because the placenta was driving it. You will still need a follow-up glucose test a few weeks later and periodic screening, since it signals a higher future risk of type 2 diabetes.

Can I still have a vaginal birth?

Often, yes. Many people with well-controlled gestational diabetes deliver vaginally. A cesarean becomes more likely mainly if your baby is estimated to be large, which good blood sugar control helps prevent.

Do I really have to prick my finger several times a day?

Usually yes, often four times a day: fasting and after meals. It is the clearest way to know your plan is working and to catch numbers that need medication. Most people find it becomes routine.

Will I get gestational diabetes again next time?

About a 50% chance in a future pregnancy. Staying active and at a healthy weight between pregnancies lowers the odds and your longer-term diabetes risk.

What should I eat?

Balanced meals with fiber, protein, and controlled portions of carbohydrates, spread through the day, keep blood sugar steadier than large or sugary meals. A dietitian can tailor this to you, which is why a referral is often part of care.

Medically Reviewed · Updated

Reviewed by Dr. Grace Lin, MD, FACOG · OB-GYN

Obstetrician-gynecologist focused on reproductive and sexual health for women: pregnancy, BV, yeast, trichomoniasis and HPV/cervical screening. Our editorial guidelines →

6 Sources

Data & references

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