Gestational diabetes diagnoses shot up 41% after a healthcare system switched from recommending a two-step to a one-step screening method — but without clinically identifiable benefits to mothers or newborns finds a new study.

"An increase would be expected given the one-step approach's lower threshold for diagnosis," Gaia Pocobelli, Ph.D., of the Kaiser Permanente Washington Health Research Institute, Seattle, and colleagues acknowledge in their article. Labor induction, neonatal hypoglycemia, nonstress testing, and insulin use all increased after the guideline change.

"The increases in labor induction and nonstress testing are also both plausible given it is recommended that women with gestational diabetes, especially those taking insulin, receive antenatal fetal surveillance and be induced by certain gestational age as a result of their increased risk of adverse outcomes," they add. And yet, "there was no apparent benefit regarding other maternal and neonatal outcomes" from the guideline switch, the authors report.

Diagnose More Diabetes, Look for More Problems

In 2010, the International Association of Diabetes and Pregnancy Study Groups proposed a new "looser" criteria for diagnosing gestational diabetes requiring one abnormal glucose value during an oral glucose tolerance test.

The criteria were adopted by the World Health Organization and American Diabetes Association, but not the American College of Obstetricians and Gynecologists, which still advises using the stricter "two-step" Carpenter-Coustan criteria that require two abnormal glucose values.

In their study, Pocobelli and colleagues compared outcomes among 4977 women screened for gestational diabetes from January 2009 to March 2011 when clinicians predominantly used a two-step guideline to outcomes of 6337 women tested April 2012 to December 2014 after the Kaiser Permanente system in Washington switched to one-step gestational diabetes screening.

One-Step Screening May Not Be Catching Women Most At Risk

Past research has found both net benefit and net harm linked to switching from two-step to one-step screening.

Although this new study's findings do not settle the continuing professional debate over the risks, benefits, and harms of the two screening methods, it does seem to be one of the first to account for time trends in the general population that occurred independently of the health care system's screening recommendations.

Still, the work could not account for other potentially influential confounding factors, including maternal diet and exercise trends, and underreported behaviors such as smoking. The use of electronic data to identify outcomes may also have led to some misclassification, the authors write.

"Our results may have been influenced by other changes in care included in the guideline such as lower blood glucose thresholds for recommending medication and an emphasis on insulin as first-line medication," they add.