This recommendation updates a previous USPSTF statement made in 2008 in which the Task Force cited a lack of sufficient evidence to assess the balance of benefits and harms of screening for gestational diabetes after 24 weeks of gestation.
"The Task Force makes evidence-based recommendations based on the overall benefits and harms of a service, regardless of whether it is standard practice or not," explained Task Force member Wanda K. Nicholson, MD, MPH, who is Associate Professor, Obstetrics and Gynecology Director, Diabetes and Obesity Core Center for Women's Health Research University of North Carolina School of Medicine, Chapel Hill, NC. "Fortunately, evidence tells us that screening and treating women for diabetes during pregnancy can reduce complications and result in healthier mothers and babies. Clinicians now have good evidence to support continuing to screen pregnant women for diabetes after 24 weeks of pregnancy," Dr. Nicholson said.
"Since the Task Force last looked at the evidence in 2008, there has been a change in thinking about how the collective benefits of preventing complications during pregnancy and birth—such as birth injuries, preeclampsia, and babies growing too large in the womb—are important," Dr. Nicholson said. "We now know, based on strong evidence, that screening all pregnant women for gestational diabetes after 24 weeks of pregnancy supports healthier mothers and babies. Because of this, the Task Force now recommends screening after 24 weeks of pregnancy," she said.
Universal screening after 24 weeks also is recommended by the American Diabetes Association, American Congress of Obstetricians and Gynecologists, The Endocrine Society, and the American Academy of Family Physicians.
There are two strategies used to screen for gestational diabetes in the United States, both of which the Task Force found can accurately identify gestational diabetes in some women. In the two step-approach—the most common of the two types—the 50-g oral glucose challenge test is performed between 24 and 28 weeks of gestation in a nonfasting state. Those women who meet or exceed the screening threshold usually receive the oral glucose tolerance test (OGTT). For this type of test, a diagnosis is made in women whose glucose levels hit or exceed two or more of the targeted thresholds for the OGTT when tested at 1, 2, and 3 hours. Alternatively, in the one-step approach, a 75-g glucose load is administered after a fasting glucose level and plasma glucose levels are evaluated after 1 and 2 hours. Gestational diabetes is diagnosed if one glucose value falls at or above the specified glucose threshold.
The USPTSF does not recommend screening earlier than 24 weeks of pregnancy in asymptomatic women as currently there is insufficient evidence to weight the benefit versus the harm of this practice. However, the USPTSF states that clinicians use their clinical judgment to determine if earlier screening is needed for women with risk factors for type 2 diabetes.
Following diagnosis, some types of initial treatment may include moderate physical activity, dietary changes, support from diabetes educators and nutritionists, and glucose monitoring, according to the USPTSF. Women who do not sufficiently respond to these interventions may be prescribed either insulin or oral hypoglycemic agents, require increased surveillance in prenatal care, or have change in delivery management.
Screening for Gestational Diabetes Mellitus. U.S. Preventive Services Task Force Recommendation Statement. Released January 14, 2014. AHRQ Publication No. 13-05191-EF-2.