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Signs of gestational diabetes in the third trimester

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SymptomsOnsetWho should be tested?Does it affect the baby?TreatmentSummary
Signs of gestational diabetes in the third trimester of pregnancy include increased thirst or peeing more often. But many people have no symptoms, which is one reason why gestational diabetes screening is an essential part of prenatal care.
Medically reviewed by Mia Armstrong, MD
Updated on

Gestational diabetes is a type of diabetes that develops during pregnancy in a person who did not previously have diabetes.

Doctors typically screen for gestational diabetes toward the end of the second trimester or the start of the third. Because people often do not experience symptoms of gestational diabetes, this screening test is critical in making an accurate diagnosis.

It’s possible to manage gestational diabetes. Treatments may include diet changes, exercise, or insulin.

Symptoms of gestational diabetes 

A pregnant person stretching. They may have signs of gestational diabetes in the third trimester.
Koldunova_Anna/Getty Images

Often, gestational diabetes does not have symptoms. When symptoms do occur, they’re typically mild, including increased thirst or more frequent urination.

Because typical pregnancy symptoms can include having to pee more often, it may be difficult to determine whether you’re experiencing symptoms of gestational diabetes.

Contact your OB-GYN if you experience any symptoms of gestational diabetes — even if they’re mild — or about any symptoms that concern you during your pregnancy.

When does gestational diabetes start?

According to the Centers for Disease Control and Prevention (CDC), if gestational diabetes does develop, it starts in the middle of the pregnancy. Doctors typically test for gestational diabetes between 24 weeks and 28 weeks of pregnancy. 

Insulin resistance starts to increase at about 16 weeks into the pregnancy. This occurs in all pregnancies, but most people are able to produce enough insulin to compensate for it. When they cannot, they develop gestational diabetes.

Who should be tested for gestational diabetes?

Any pregnant person should be tested for gestational diabetes starting at week 24 or later during the pregnancy, according to the U.S. Preventive Services Task Force. This recommendation includes people who do not have any symptoms of gestational diabetes.

Testing is the only way to confirm a diagnosis of gestational diabetes. Learn more about gestational diabetes testing, including how to prepare and what to expect.

Early screening for gestational diabetes

Doctors may recommend earlier testing for gestational diabetes in people with certain risk factors, including:

  • family history of diabetes
  • one or more previous pregnancies with gestational diabetes
  • polycystic ovary syndrome (PCOS)
  • an A1C of 5.7% or higher
  • blood pressure of 140/90 mm Hg or higher

Talk with your OB-GYN about your individual risk factors and the right timing of gestational diabetes testing during your pregnancy.

Does gestational diabetes cause problems for the baby?

Gestational diabetes starts in late pregnancy after the baby’s body has already substantially developed. According to the American Diabetes Association (ADA), issues with fetal development are more likely if someone has diabetes before they become pregnant.

By following your recommended treatment plan, you can have a healthy baby with gestational diabetes. However, without effective treatment, gestational diabetes can increase the risk of complications for both the parent and the baby. This can include:

  • Increased birth weight: Too much blood sugar may cause the baby to be larger than usual. This raises the likelihood of needing a C-section delivery, which typically has a longer recovery time than vaginal delivery.
  • High blood pressure (preeclampsia): Preeclampsia is a potentially life threatening condition and a leading cause of premature birth. In severe cases, it develops into eclampsia, which is the onset of seizures in a pregnant person who has not previously experienced seizures.
  • Low blood sugar (hypoglycemia): Your blood sugar might become low when taking diabetes medications such as insulin, or the baby’s blood sugar may quickly drop after birth. Doctors will monitor blood sugar levels in both the parent and child during and after delivery.

How is gestational diabetes treated?

Diet and physical activity are essential to keep your blood glucose level in the target range during pregnancy. A healthcare professional, such as a nutritionist or registered dietician, can help you choose foods that are healthy for you and your fetus. 

If diet and exercise are not effective on their own, a doctor might recommend taking insulin to reduce sugar levels.

Medications such as metformin (Riomet, Glumetza) and glyburide are not first-line agents to treat gestational diabetes, as they both can affect the fetus. The ADA’s guidelines also note that other diabetes medications besides insulin do not have long-term safety data for treatment of gestational diabetes. 

Your doctor or healthcare professional will discuss your individual treatment options to develop the right plan for you.

If you receive a gestational diabetes diagnosis in the second or third trimester, you typically continue to monitor your blood glucose level for the rest of your pregnancy. This includes using an at-home blood glucose meter to test before meals and at other times of the day as per a doctor’s recommendation. 

After delivery

People who develop gestational diabetes are 10 times more likely to develop type 2 diabetes than those who did not experience gestational diabetes during pregnancy.

For this reason, if you experience gestational diabetes, the CDC recommends you be tested for diabetes 6–12 weeks after giving birth, then every 1–3 years indefinitely.

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Gestational diabetes often has no symptoms, but when they do occur, they can include feeling thirsty more often or increased urination.

Gestational diabetes testing is the only way to get an accurate diagnosis. Doctors typically test for gestational diabetes between weeks 24 and 28 of pregnancy, regardless of whether someone is experiencing symptoms.

If you receive a diagnosis, your doctor will discuss how to monitor your glucose with an at-home blood glucose meter. Diet, exercise, and insulin (if necessary) can often manage your blood sugar and allow you to have a healthy pregnancy and delivery.

Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.

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