Comparing ADA vs. ACOG Approaches for Gestational Diabetes Screenings

Teresa Hillier, MD

A new trial from clinicians at Kaiser Permanente suggests there was no significant difference in perinatal and maternal outcomes when comparing a pair of screening procedures for diagnosis of gestational diabetes.

A comparison of the American Diabetes Association’s (ADA) 1-step protocol versus the 2-step approach recommended by the American College of Obstetricians and Gynecologists (ACOG), results of the trial indicate the ADA method may be more effective for identifying gestational diabetes but did not contribute to significant differences in outcomes.

"We know that screening and diagnosing women with gestational diabetes improves outcomes for mothers and babies," said lead author Teresa Hillier, MD, MS, lead investigator and clincian at Kaiser Permanente Northwest's Center for Health Research and Kaiser Permanente's Hawaii Center for Integrated Health Care Research, in a statement. “Our trial was designed to determine whether there were any differences in outcomes between the two approaches. The 1-step method diagnoses twice as many women, typically leading to treatment of women with milder gestational diabetes, but we found no evidence that this higher diagnosis rate led to differences in outcomes."

With these approaches representing some of the most commonly used protocols for screening of gestational diabetes and no head-to-head trials examining how the differing approaches influences outcomes, Hillier and a team of colleagues sought to fill this apparent gap in knowledge to improve care of these patients. To do so, investigators designed their study as a pragmatic, randomized trial in a cohort of women recruited from Kaiser Permanente medical centers in Hawaii and Oregon.

Briefly, the 1-step screening involved a glucose-tolerance test obtained after the oral administration of a 75 glucose load in the fasting state while the 2-step screening involved a glucose challenge test after the administration of a 50 g glucose load in a nonfasting state followed by an oral- glucose tolerance test with a 100 g glucose load in the fasting state, if the original challenge was positive.

In total, 23,792 women underwent randomization—of note, women with multiple pregnancies during the trial could have been assigned to more than a single type of screening. Of the 23,792 women eligible for randomization, 94% completed screening, which included 66% of the women in the ADA group and 92% in the ACOG group.

The primary outcomes of the analysis were a diagnosis of gestational diabetes, large-for-gestational-age infants, a perinatal composite outcome, gestational hypertension or preeclampsia, and primary cesarean section. The perinatal composite outcome included stillbirth, neonatal death, shoulder dystocia, bone fracture, or any arm or hand nerve palsy related to birth injury. Upon analysis, results indicated gestational diabetes was diagnosed in 16.5% of women assigned to the 1-step ADA approach and among 8.5% of those randomized to the 2-step ACOG approach (unadjusted Relative Risk [RR], 1.94; 97.5% CI, 1.79-2.11).

Intention-to-treat analyses revealed the respective incidences for each of the primary outcomes were 8.9% and 9.2% for large-for-gestational-age infants (RR, 0.95; 97.5% CI, 0.87-1.05), 3.1% and 3.0% for perinatal composite outcome (RR, 1.04; 97.5% CI, 0.88-1.23), 13.6% and 13.5% for gestational hypertension or preeclampsia (RR, 1.00; 97.5% CI, 0.93-1.08), and 24.0% and 24.6% for primary cesarean section (RR, 0.98; 97.5% CI, 0.93-1.02) for the 1-step and 2-step approaches, respectively.

"What this large-scale clinical trial illustrates is that the 2-step screening method appears to be preferred by patients and providers, and had a lower screen-positive rate, and led to outcomes that were not different from the 1-step method," added Keith Ogasawara, MD, chief perinatologist, Department of Obstetrics and Gynecology with Kaiser Permanente in Hawaii, in the aforementioned statement.

This study, “A Pragmatic, Randomized Clinical Trial of Gestational Diabetes Screening,” was published in the New England Journal of Medicine.