Gestational Diabetes Screening Revisited

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Gestational Diabetes Screening Revisited

Many medical organizations, such as the American Diabetes Association and the American College of Obstetricians and Gynecologists, urge that all pregnant women be screened for gestational diabetes. Gestational diabetes is a temporary (usually) form of diabetes that occurs in as many as an estimated one out of 10 pregnant women. But the question that remains is: when should such screening take place?

In 2014, the U.S. Preventive Services Task Force (USPSTF), which defines itself as an “independent, volunteer panel of national experts in disease prevention and evidence-based medicine,” addressed just that question. It recommended that all women be screened for gestational diabetes at 24 weeks of pregnancy, even if they have no symptoms. Also at that time, in a move praised by diabetes experts, it changed the recommendation from an “I” (insufficient evidence) to a B-level, which is its second-highest level of strength.

Seven years later, the USPSTF has now revisited the issue and published their report in JAMA, the Journal of the American Medical Association. The task force, which was headed by Karina W. Davidson, PhD, of the Feinstein Institutes for Medical Research in New York, based its analysis on an evidence report conducted by Jennifer Pillay, MSc, of the University of Alberta and her colleagues.

That report was the result of a survey of 76 studies researching gestational diabetes screening. Some 20 of these studies were carried over from the 2014 USPSTF report; the rest were new. These studies, which rated the accuracy of various screening tests for gestational diabetes, were said to be of “fair or good quality.” The screening methods evaluated included fasting plasma glucose level, HbA1c (A1C0 concentration, screening based on risk factors, and the 50-g OGCT, a glucose tolerance test commonly used in gestational diabetes screening that tells how fast glucose is cleared from the blood.

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Recommendation: Gestational diabetes screening begin at 24 weeks

The new task force report found sufficient evidence that gestational diabetes screening improves the health of both mother and child. It also concluded that treatments for gestational diabetes (dietary or medical therapies, or both) are related to improvements in the results of pregnancy. Specifically, the researchers concluded that screening led to lower rates of caesarean delivery, the birth injury known as shoulder dystocia, other birth injuries, macrosomia (a baby larger than average), and the need for infant intensive care. The report concluded by continuing to recommend that gestational diabetes screening begin at 24 weeks. It noted that screening earlier than that had been shown to carry some risks, such as depression or anxiety in the mother and poor hospital experiences, which could lead to lower rates of breastfeeding immediately after delivery. In addition, treatment for gestational diabetes before 24 weeks carried such risks as low blood sugar in mother and child, a low birth weight, and maternal stress. These risks were not found to develop after 24 weeks.

The JAMA report was accompanied by an editorial cowritten by Cuilin Zhang, MD, and Patrick Catalano, MD, in which they pointed to “inadequate evidence that commonly used screening tests can accurately detect glucose intolerance in early pregnancy.” “Effective early screening to identify women at high risk for gestational diabetes and timely intervention may represent an important approach,” they said, “More studies … are warranted to inform future recommendations.”

Before the new report was published in JAMA, the authors posted a request for public comments on the USPSTF website. Several responses asked for specific recommendations on which screening test is to be preferred for gestational diabetes. The task force noted that although several tests can accurately identify the condition, they were unable to recommend “any single specific test.”

Want to learn more about gestational diabetes? Read “Gestational Diabetes: Are You at Risk?” and “Treating Gestational Diabetes.”

Joseph Gustaitis

Joseph Gustaitis

Joseph Gustaitis on social media

A freelance writer and editor based in the Chicago area, Gustaitis has a degree in journalism from Columbia University. He has decades of experience writing about diabetes and related health conditions and interviewing healthcare experts.

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