Gestational diabetes screening should take place at 24 weeks

January 16, 2014

All pregnant women should be screened for gestational diabetes mellitus at 24 weeks gestation, even if they have no symptoms, according to new recommendations from the U.S. Preventive Services Task Force (USPSTF).

All pregnant women should be screened for gestational diabetes mellitus at 24 weeks gestation, even if they have no symptoms, according to new recommendations from the U.S. Preventive Services Task Force (USPSTF).

The B-level recommendation from USPSTF, published in the Annals of Internal Medicine, aligns with other medical organizations, including the American Society of Clinical Endocrinologists, the American Diabetes Association (ADA), and the American College of Obstetricians and Gynecologists (ACOG).

Gestational diabetes, which occurs in 1% to 25% of pregnancies, puts women at increased risk for maternal and fetal complications, such as preeclampsia, fetal macrosomia, and neonatal hypoglycemia. Women diagnosed with gestational diabetes are at increased risk for developing type 2 diabetes, which may occur 5 to 15 years following delivery, according to the USPSTF.

The new recommendation from the USPSTF brings the group’s position closer to that of ACOG and other professional organizations that have long recommended screening all pregnant women for gestational diabetes, according to William H. Barth, Jr, MD, chief, Division of Maternal-Fetal Medicine at Massaschusetts General Hospital in Boston.

“It’s nice to see the various governing bodies and institutions growing closer to a common position; this decreases confusion for patients and clinicians,” Dr Barth said.

“For policy-makers, the coalescence of previously disparate recommendations on screening for gestational diabetes should be helpful; the evidence to support screening and treatment is strong,” Dr Barth said.

How to screen is another issue and remains controversial, according to Dr Barth.

“ACOG and the National Institutes of Health Consensus Development Conference panel members have concluded that for the time being, a traditional approach is best,” he said. “The ADA and the International Association of the Diabetes and Pregnancy Study Groups [IADPSG] continue to advocate for a 1-step approach. The differences in these recommendations stem largely from the unknown benefit and impact of the IADPSG 1-step approach on outcomes and resource utilization; in effect, the IADPSG guidelines would change the incidence from about 7% in the United States to almost 18%-and there is insufficient evidence to show an overall benefit in this additional 10% of all pregnant women.

“Concerns include over-medicalization of previously normal pregnancies and the huge resource implications that would follow,” Dr Barth added.

Gestational diabetes, which occurs in 1% to 25% of pregnancies, puts women at increased risk for maternal and fetal complications, such as preeclampsia, fetal macrosomia, and neonatal hypoglycemia. Women diagnosed with gestational diabetes are at increased risk for developing type 2 diabetes, which may occur 5 to 15 years following delivery, according to the USPSTF.

“Many practices have been instituting these recommendations, but it’s wonderful to have received a B-level recommendation from the USPSTF,” said Michelle Hilaire, PharmD, clinical pharmacist at the Fort Collins Family Medicine Center, a service of University of Colorado Health, in Fort Collins, Colo.

“The earlier that we can diagnose and begin treating women with gestational diabetes, we can reduce maternal and fetal complications,” Dr Hilaire told FormularyWatch.  “Testing between 24 to 28 weeks allows us to help women make smarter choices throughout their pregnancy. This will most likely lead to less complications during delivery.”

As many as 1 in 5 women may develop gestational diabetes, but, traditional testing strategies only identify about 25% of the cases. Women who go undiagnosed are at an increased risk of having an overly large baby, which can complicate delivery.

The Endocrine Society is encouraged by USPSTF’s efforts to promote gestational diabetes screening and recommends going a step further to identify undiagnosed type 2 diabetes cases before harmful pregnancy complications can develop.

The Society also recommends universal diabetes testing for women at the first prenatal visit in its Diabetes and Pregnancy Clinical Practice Guideline that was published in the November 2013 issue of the Society’s Journal of Clinical Endocrinology and Metabolism. The test should be done before 13 weeks’ gestation or as soon as possible thereafter.

“Given that many cases of type 2 diabetes are undiagnosed, it’s important to ascertain early in pregnancy whether women have this condition,” said Ian Blumer, MD, of the Charles H. Best Diabetes Centre in Whitby, Ontario, Canada, and chair of the taskforce that authored the guideline. “Untreated diabetes poses serious risks to the mother and the fetus, so it is important to reduce the chance of complications through early diagnosis and treatment.”

When pregnant women are screened for gestational diabetes at 24 to 28 weeks gestation, the Endocrine Society recommends using a one-step testing approach in line with the consensus panel of the International Association of the Diabetes and Pregnancy Study Groups’ protocol. This involves pregnant women taking a 75-g oral glucose tolerance test, which is more sensitive and can help physicians diagnose more cases. This differs from the 50-g oral glucose challenge test, which is commonly used in the United States. As the USPSTF noted in its statement, many pregnant women receive this test and are only given the oral glucose tolerance test if the first test yields abnormal results.

Women diagnosed with gestational diabetes should be initially counseled about moderate physical activity, dietary changes, glucose monitoring, and support from a diabetes educator and nutritionist. If these interventions are insufficient for management of glucose, insulin or oral hypoglycemic agents should be prescribed. Increased surveillance of prenatal care is warranted, according to the USPSTF.