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What is gestational diabetes?
Gestational diabetes is high blood sugar that first occurs during pregnancy. High blood sugar can cause problems for you and your baby. But with treatment, most women can control their blood sugar and have healthy babies. Blood sugar levels usually go back to normal after the baby is born.
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 the mother's 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. Some women 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. Most women get this screening test for gestational diabetes between the 24th and 28th weeks of pregnancy.
How is gestational diabetes treated?
Controlling your blood sugar is the key to preventing problems during pregnancy and birth. You may be able to control your blood sugar if you change the way you eat and get regular moderate exercise. You may also need to take diabetes medicine or give yourself insulin shots.
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During pregnancy, the placenta makes several other hormones. Some of these hormones make it hard for insulin to do its job. The mother's body needs to make more insulin to control sugar levels. Gestational diabetes develops when her body can't make enough insulin to keep blood sugar levels in a safe range.
What Increases Your Risk
You are more likely to have gestational diabetes if you:
- Are older when you become pregnant.
- Are very overweight (body mass index [BMI] of 30 or higher).
- Have had gestational diabetes before.
- Have a family history of diabetes.
- Have a history of prediabetes.
Talk to your doctor about your risks.
In some women, 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. Regular exercise can also help keep your blood sugar level within a target range. This can help prevent gestational diabetes.
Gestational diabetes may not cause symptoms, so you need to be tested for it.
Sometimes a pregnant woman has been living with 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.
Most pregnant women urinate more often and feel more hungry. So having these symptoms doesn't always mean that a woman has diabetes. But if you have these symptoms at any time during pregnancy, talk with your doctor so that you can be tested for diabetes.
Most women who have gestational diabetes give birth to healthy babies. But sometimes high blood sugar causes problems during pregnancy or birth. For example:
- The mother may have high blood pressure caused by preeclampsia.
- The baby may grow too large. If a developing baby gets too much sugar, the baby may grow larger than normal. A large baby can be injured during vaginal birth and may need to be delivered by cesarean section.
- The baby's blood sugar level may drop too low after birth. The baby may need to be given extra sugar.
- The baby may develop other treatable problems after birth. These include low blood calcium levels, high bilirubin levels, and too many red blood cells.
Keeping your blood sugar level within a target range will reduce your risk of problems during pregnancy and birth.
Gestational diabetes will probably go away after your baby is born. But you will have a greater risk of:
- Gestational diabetes in a future pregnancy.
- Type 2 diabetes later in life.
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, 300 mg/dL for two or more readings).
- You have blood sugar that stays lower than the level the doctor has set for you (for example, 70 mg/dL for two or more readings).
- You have symptoms of low blood sugar, such as:
- Feeling nervous, shaky, and weak.
- Extreme hunger and slight nausea.
- Dizziness and headache.
- Blurred vision.
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.
Most women get tested for gestational diabetes between the 24th and 28th weeks of pregnancy. The method of testing may vary. Experts think that each method works as well as the other one.footnote 1
The first method is done in two steps.
- 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.
- 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.
Some experts use 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 will 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 along with other information can help your doctor decide on your care.
- Nonstress 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 a similar test every month during your pregnancy. The A1c test estimates your average blood sugar level over the previous 2 to 3 months.
Your doctor may also want you to check your blood sugar at home. This helps you know if your blood sugar level is within a target range.
Tests during labor and delivery
You and your baby will be monitored closely during labor and delivery. You'll have blood sugar tests to make sure your blood sugar level is within a target range. Fetal heart monitoring will be done to see how well your baby is doing during labor.
Tests after delivery
You and your baby will be monitored closely after delivery.
- Your blood sugar level will be watched for the first few hours. Usually blood sugar levels quickly return to normal.
- Your baby's blood sugar level will also be watched. 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 (IV).
You may have a follow-up glucose tolerance test 4 to 12 weeks after your baby is born or after you stop breastfeeding your baby.
- If your blood sugar level is normal, experts recommend that you get tested for type 2 diabetes at least every 3 years.
- If your blood sugar is slightly high, you may have prediabetes. You may need to be tested for diabetes every year.
Gestational diabetes will probably go away after your baby is born. But you are at risk for it in a future pregnancy. You are also at increased risk for type 2 diabetes later in life. It's a good idea to be tested for diabetes both before you get pregnant again and early in your pregnancy.
Controlling your blood sugar is the key to preventing problems during pregnancy and birth. You may be able to control your blood sugar with healthy eating and regular moderate exercise. If you keep up with these healthy habits, they can help prevent gestational diabetes in a future pregnancy. They can also help prevent type 2 diabetes later in life.
You'll need to check your blood sugar at home to see if it's staying in a target range. If it isn't, you may need to take diabetes medicine or give yourself insulin shots.
It's also important to have regular medical checkups. At each visit, your doctor will do tests to see how you and your baby are doing. You and your baby will be monitored closely during labor and after delivery.
These steps can help you manage gestational diabetes and have a healthy pregnancy. And if you continue with healthy habits, you may be able to prevent diabetes in the future.
- Eat healthy foods.
Changing what, when, and how much you eat can help keep your blood sugar level in a target range. A registered dietitian can help you make a healthy eating plan and teach you how to limit carbohydrates.
- Get regular exercise.
This can help you control your blood sugar level. Try low-impact activities, such as walking and swimming.
- Try to be active 30 minutes a day, at least 5 days a week.footnote 2
- If you haven't been exercising regularly, talk to your doctor before you start.
- Check your blood sugar levels.
Do a home blood sugar test at least daily. 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 discuss your blood sugar levels, eating and exercise, and how to manage weight gain.
- Monitor your baby's well-being.
Your doctor may have you do kick counts. Tell your doctor if you think your baby has been moving less than usual.
- Take diabetes medicine or insulin shots if needed.
This helps control your blood sugar if it can't be controlled with healthy eating and exercise. Staying in your target blood sugar range may be harder as you approach your due date.
You can likely treat gestational diabetes by changing the way you eat and exercising more often. If these changes don't keep your blood sugar level within a target range, you may need to take diabetes medicine. Examples include metformin, glyburide, and insulin.
You may also need to take insulin if your doctor thinks that your baby is getting too large. 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 on 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
Most women with gestational diabetes don't have a problem with low blood sugar (hypoglycemia). But you are at risk for low blood sugar if you take insulin shots or some diabetes medicines. Low blood sugar may occur if you do any of the following:
- Skip meals or don't eat enough
- Exercise more than usual
- Take too much insulin
- Take too much diabetes medicine in one day
Be sure to treat low blood sugar right away so that it doesn't harm you or your baby.
- American Diabetes Association (2021). Standards of medical care in diabetes—2021. Diabetes Care, 44(Suppl 1): S1–S232. Accessed January 5, 2021.
- U.S. Department of Health and Human Services (2018). Physical Activity Guidelines for Americans, 2nd ed. https://health.gov/paguidelines/second-edition. Accessed July 9, 2018.
Current as of: December 2, 2020
Author: Healthwise Staff
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
Femi Olatunbosun MB, FRCSC - Obstetrics and Gynecology
Current as of: December 2, 2020
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