This blog has covered the topic of gestational diabetes mellitus several times. Recent big news in this arena is the recommendation from the U.S. Preventative Services Task Force (USPSTF) that all pregnant women be screened for gestational diabetes mellitus (GDM) after 24 weeks of gestation.
The USPSTF is an "independent panel of non-Federal experts in prevention and evidence-based medicine and is composed of primary care providers." Their job is to "conduct scientific evidence reviews of a broad range of clinical preventive health care services and develop recommendations for primary care clinicians and health systems." For the USPSTF to "recommend" a practice means that there is evidence to suggest that the benefits of that practice outweigh the harms.
First, a few facts about GDM:
- Each year, about 4 million women give birth and about 240,000 of these women (6%) develop diabetes during their pregnancy. The actual number of women identified as having GDM depends on the screening test that is used.
- Over the last 2 decades, GDM has become more common because more women are at risk of developing diabetes. Risk factors include being overweight or obese or having a family history of diabetes.
- Even though GDM usually goes away after pregnancy ends, it still puts the mother and the fetus at risk of serious health issues. For the mother these include preeclampsia and an increased chance for the development of type 2 diabetes after pregnancy. For the fetus these include macrosomia (a high birth weight which makes delivery difficult and Cesarean section more likely), shoulder dystocia, and an increased risk of becoming obese during childhood.
The USPSTF recommended screening for GDM after 24 weeks of pregnancy in all women who do not already have symptoms of diabetes. They gave this recommendation a grade of "B," meaning that there is a high certainty that there is moderate certainty that the net benefit of GDM screening is moderate to substantial.
Women benefit from GDM screening because it:
- Identifies those who have GDM and who should be treated (usually with diet modifications, glucose monitoring, and, if needed, insulin therapy).
- Lowers the risk of preeclampsia, fetal macrosomia, and shoulder dystocia.
The harms of screening were minimal and included:
- Anxiety in some women.
- The use of unnecessary tests and services.
The Task Force did not find sufficient evidence to support screening for GDM before 24 weeks of pregnancy and gave that statement a grade of "I," meaning was insufficient evidence to assess the balance of the benefits and harms of GDM screening.
The USPSTF did not make any recommendations regarding what GDM screening test to use. As this blog has noted before, there is no universally accepted method for diagnosing GDM and this has resulted in 5 different approaches (and considerable debate).