What is Gestational Diabetes?

What is Gestational Diabetes?

• Gestational diabetes mellitus (GDM) is a form of diabetes that causes high blood glucose during pregnancy.
• During pregnancy, the placenta releases hormones that can cause insulin resistance, leading to higher blood glucose if insulin levels aren’t enough.
• GDM is commonly diagnosed as high blood glucose starting between 24 and 28 weeks of pregnancy.
• About 1 in 10 pregnant women is diagnosed with gestational diabetes.
• Occasionally it is diagnosed earlier in pregnancy, which may indicate high blood glucose prior to pregnancy.

What Happens When Blood Glucose is High in Pregnancy?

• High blood glucose is known to cause adverse outcomes in pregnancy.
• In the first trimester, high blood glucose can cause pregnancy loss or malformations in the baby.
• Later in pregnancy, as a mother’s elevated blood glucose crosses the placenta, it will cause the baby to produce insulin in response.
• Excessive insulin leads to excessive growth of the baby.
  • This can cause issues during labor and delivery, increasing the cesarean section rate as well as neonatal hypoglycemia (baby’s low blood glucose at birth).
• In addition, babies who have grown excessively are at risk for childhood obesity and type 2 diabetes.

What are the Signs of Gestational Diabetes?

• Some women may experience thirst, frequent urination, or exhaustion when they have high blood glucose levels.
  • All of these symptoms, however, are common in pregnancy.
• Symptoms are not used to diagnose or determine testing for gestational GDM.

How is Gestational Diabetes Diagnosed?

• GDM is diagnosed through either the “Glucose Challenge Test” or one of two “Glucose Tolerance Tests.”
  • Different healthcare providers use different tests depending on their practice and the results of each test.
• In addition, many also order an A1c test to determine how high blood glucose levels have been over the previous 3 months.

Who Should Be Tested for Gestational Diabetes?

• All women should be tested for GDM no later than 24-28 weeks.
• Women who are at higher risk for GDM should be tested earlier in pregnancy.

What Makes a Woman Higher Risk for Gestational Diabetes?

• GDM in a previous pregnancy
• History of prediabetes (A1c 5.7-6.4)
• Elevated Body Mass Index (BMI)
• A previous baby larger than 4000 gm (about 9 pounds)
• History of Polycystic Ovarian Syndrome (PCOS)
• History of hypertension or metabolic disease
• Advanced maternal age (>35)
• Lack of physical activity
• High-risk ethnicity (African American, Latina, Asian American, Native American, Pacific Islander)
• Family history of diabetes in a first-degree relative

Can Gestational Diabetes Be Prevented?

There are no evidence-based recommendations specifically for preventing GDM. However, getting preconception care to check for preexisting diabetes is extremely important.

Also, starting pregnancy with a normal BMI and a healthy lifestyle, including both diet and exercise, are important for overall health in pregnancy.

Read A (Gestational Diabetes) Wake Up Call by Casey Tunguz.

Note: This article is part of our library of resources for Forms of Diabetes.