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Gestational Diabetes

Condition Basics

This information has been translated into other languages – see the links at the bottom of this page.

What is gestational diabetes?

Gestational diabetes is high blood sugar that is first diagnosed during pregnancy. High blood sugar can cause problems for you and your baby. With treatment and lifestyle changes, you can manage your blood sugar and have a healthy baby. Blood sugar levels often go back to normal after you give birth.

What causes it?

Insulin is a hormone that helps your body use and store sugar. During pregnancy, the placenta makes other hormones that make it hard for insulin to control blood sugar. Gestational diabetes develops when your body can't make enough insulin to keep blood sugar levels in a safe range.

What are the symptoms?

Gestational diabetes may not cause symptoms, so you need to be tested for it. You may have symptoms such as being very thirsty or having blurred vision.

How is it diagnosed?

The oral glucose tolerance test is used to diagnose the condition. You may get this screening test for gestational diabetes between the 24th and 28th weeks of pregnancy.footnote 1

How is gestational diabetes treated?

Managing your blood sugar is the key to preventing problems during pregnancy, birth, and after your baby is born. You may be able to manage your blood sugar with a healthy diet and regular exercise. You may also need to give yourself insulin shots or take diabetes medicine.

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Gestational Diabetes

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Cause

Insulin is a hormone made by the pancreas. It helps your body use and store the sugar from the food you eat. This keeps your blood sugar level in a safe range.

During pregnancy, the placenta makes several other hormones. Some of these hormones make it hard for insulin to do its job. So your body needs to make more insulin. Gestational diabetes develops when your body can't make enough insulin to keep blood sugar levels in a safe range.

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What Increases Your Risk

You are more likely to have gestational diabetes if you:footnote 1

  • Are very overweight (body mass index [BMI] of 30 or higher).
  • Are older when you become pregnant.
  • Have had gestational diabetes before.
  • Have a family history of diabetes.
  • Have a history of prediabetes.

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Prevention

Sometimes gestational diabetes can't be prevented. But you may lower your risk if you stay at a healthy weight and don't gain too much weight during pregnancy. Healthy eating and regular exercise can also help keep your blood sugar level in a safe range. This can help prevent gestational diabetes.

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Symptoms

Gestational diabetes may not cause symptoms, so you need to be tested for it.

You could have another type of diabetes without knowing it. Common symptoms of high blood sugar include:

  • Feeling very thirsty.
  • Urinating more often than usual.
  • Feeling very hungry.
  • Having blurred vision.

It's common to urinate more often and feel more hungry during pregnancy. So having these symptoms doesn't always mean that you have gestational diabetes. But if you have these symptoms at any time during pregnancy, talk with your doctor. Your doctor can help you get tested for diabetes.

What Happens

Even if you have gestational diabetes, you can give birth to a healthy baby. But sometimes high blood sugar causes problems during pregnancy, birth, or after your baby is born. For example:

  • You may have high blood pressure caused by preeclampsia.
  • Your baby may grow too large. Babies who get too much sugar can grow larger than normal. A large baby can be too big for a vaginal birth and may need to be delivered by caesarean section.
  • Your baby's blood sugar level may drop too low after birth. The baby may need to be given extra sugar.
  • Your baby may develop other treatable problems after birth. These may include low blood calcium levels, high bilirubin levels, or too many red blood cells.
  • You're more likely to get gestational diabetes in a future pregnancy.
  • You have a greater risk of type 2 diabetes later in life.

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When to Call a Doctor

Call 911 or other emergency services right away if:

  • You passed out (lost consciousness), or if you suddenly become very sleepy or confused. (You may have very low blood sugar, called hypoglycemia.)

Call a doctor now if:

  • You are sick and can't control your blood sugar. Your doctor may have given you instructions on how to control your blood sugar when you are sick.
  • You have been vomiting or have had diarrhea for more than 6 hours.
  • You have a blood sugar level that stays higher than the level the doctor has set for you (for example, 17.0 mmol/L for two or more readings).
  • You have blood sugar that stays lower than the level the doctor has set for you (for example, 4.0 mmol/L for two or more readings).
  • You have symptoms of low blood sugar, such as:
    • Sweating.
    • Feeling nervous, shaky, and weak.
    • Extreme hunger and slight nausea.
    • Dizziness and headache.
    • Blurred vision.
    • Confusion.

Check with your doctor if:

  • You often have problems with high or low blood sugar levels.
  • You have questions or want to know more about gestational diabetes.

Check your symptoms

Exams and Tests

Testing for gestational diabetes

The oral glucose tolerance test is used to diagnose the condition.

You may be tested for gestational diabetes between the 24th and 28th weeks of pregnancy. There are two testing methods.

The first method is done in two steps.

  1. A blood sample is taken after you drink a liquid that contains sugar (glucose). If you don't have a lot of sugar in your blood, you don't have gestational diabetes.
  2. If you have a lot of sugar in your blood, you will do the oral glucose tolerance test (OGTT). If it shows that you have a lot of sugar in your blood, you may have gestational diabetes.

The second method uses a one-step method that is a version of the OGTT. If it shows that you have a lot of sugar in your blood, you may have gestational diabetes.

Tests during pregnancy if you have gestational diabetes

Your doctor will check your blood pressure at every visit. You'll also have tests throughout your pregnancy to check your baby's health. These include:

  • Fetal ultrasound. It may be used to estimate the age, weight, and health of your baby. It also can measure your baby, including the size of the head and abdomen. These measurements, plus other information, can help your doctor decide on your care.
  • Non-stress test. It records your baby's heart rate while your baby is moving and not moving. It can show how well your baby is doing.

Your doctor may recommend having a hemoglobin A1c or similar test every month during your pregnancy. The A1c test estimates your average blood sugar level over the previous 2 to 3 months.

You and your doctor will talk about how often to check your blood sugar at home. This helps you know if your blood sugar level is in your target range.

Tests during labour and delivery

You and your baby will be watched closely during labour and delivery. You'll have blood tests to make sure your blood sugar level is in a safe range. Fetal heart monitoring will be done to see how your baby is doing during labour.

Tests after delivery

You and your baby will be watched closely after delivery.

  • Your blood sugar level will be checked for the first few hours. Blood sugar levels often return to normal quickly.
  • Your baby's blood sugar level will also be checked. If your blood sugar levels were high during pregnancy, your baby's body will make extra insulin for several hours after birth. This extra insulin may cause your baby's blood sugar to drop too low. Your baby may need extra sugar. This may be given as a drink or through a needle in a vein (I.V.).

Long-term checkups

You may have a follow-up glucose tolerance test 6 weeks to 6 months after your baby is born.footnote 1

  • If your blood sugar level is normal, experts recommend that you get tested for type 2 diabetes at least every 3 years.footnote 1
  • If your blood sugar is slightly high, you may have prediabetes. You may need to be tested for diabetes every year.

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Treatment Overview

Managing your blood sugar is the key to preventing problems during pregnancy, birth, and after your baby is born.

You may be able to do this with healthy eating and regular exercise. Keeping up with these healthy habits can help prevent gestational diabetes in a future pregnancy. It can also help prevent type 2 diabetes later in life.

You may need to check your blood sugar at home to see if it's staying in your target range. If it isn't, you may need to take diabetes medicine or give yourself insulin shots.

You'll have regular checkups with your doctor. The doctor will do tests to see how you and your baby are doing. You and your baby will be watched closely during labour and after delivery.

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Self-Care

These steps can help you keep your blood sugar in your target range and have a healthy pregnancy. They can also help you prevent diabetes after the birth.

  • Make healthy food choices.

    Eat plenty of lean protein, fruits, and vegetables. Follow your meal plan to know how much carbohydrate you need for meals and snacks.

  • Get regular exercise.

    Try low-impact activities, such as walking and swimming. Try to get 2½ hours of moderate intensity exercise at least three days a week.footnote 2

    If you're increasing your activity, talk to your doctor before you start.

  • Check your blood sugar levels.

    Ask your doctor how often to test your blood sugar.

  • Get regular checkups.

    Your doctor will do tests to check on you and your baby. You'll talk about your blood sugar levels, eating and staying active, and how to manage pregnancy weight gain.

  • Take insulin shots or diabetes medicine if needed.

    This helps control your blood sugar if it can't be managed with healthy eating and regular exercise. Blood sugar can be harder to manage as you approach your due date.

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Medicines

Diabetes medicine, such as insulin or pills, can help keep your blood sugar level in your target range. If you need to take insulin, you'll learn how to give yourself an insulin shot.

How much insulin you need depends on how much you weigh and how close you are to your due date. You may need more insulin as you get closer to your delivery date. That's because over time the placenta makes more and more hormones. This makes it harder and harder for insulin to do its job.

Risk of low blood sugar with insulin and diabetes medicines

You may not have low blood sugar (hypoglycemia) when you have gestational diabetes. But you are at risk for low blood sugar if you take insulin shots or some diabetes medicines. Low blood sugar may happen if you:

  • Skip meals or don't eat enough.
  • Are more active than usual.
  • Take too much insulin.
  • Take too much diabetes medicine in one day.

Learn more

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Related Information

References

Citations

  1. Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Diabetes and pregnancy. Canadian Journal of Diabetes, 42(Suppl 1): S255–S282. DOI: 10.1016/j.jcjd.2017.10.038. Accessed October 15, 2018. [Erratum in Canadian Journal of Diabetes 42(3): 337. DOI: 10.1016/j.jcjd.2018.04.006.] Accessed October 12, 2018.
  2. Mottola MF, et al. (2018). Canadian guideline for physical activity throughout pregnancy. No. 367-2019. Journal of Obstetrics and Gynaecology Canada, 40(11): 1528–1537. DOI: 10.1016/j.jogc.2018.07.001. Accessed April 1, 2020.

Credits

Adaptation Date: 11/27/2023

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

Adapted with permission from copyrighted materials from Healthwise, Incorporated (Healthwise). This information does not replace the advice of a doctor. Healthwise disclaims any warranty and is not responsible or liable for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.