Gestational Diabetes Screening Methods Comparable in Maternal Outcomes

Teresa Hillier, MD

A new, pragmatic randomized clinical trial has reported that a one-step approach to gestational diabetes screening was linked to twice as many diagnosid incidences as compared with a two-step screening approach.

Nonetheless, the type of screening did not have an effect on risk for adverse maternal or perinatal outcomes.

“There is no scientific consensus on how best to diagnose gestational diabetes,” noted Teresa Hillier, MD, Center for Health Research, Kaiser Permanente Northwest, and her investigative team, thus highlighting the inherent advantages and disadvantages of either screening methods, including level of logistical convenience and diagnostic cutoff thresholds.

“The National Institutes of Health Consensus Development Conference on diagnosing gestational diabetes mellitus recommended that a randomized trial compare these approaches with respect to clinically important outcomes,” the team wrote.

One-Step or Two-Step Screening

Therefore, Hillier and colleagues evaluated a total of 23,792 women, all of whom were receiving care at Kaiser Permanente Northwest and Kaiser Permanente Hawaii.

All women were randomly assigned 1:1 to a one-step or two-step approach to screening.

The one-step approach included a glucose-tolerance test, where the blood glucose level was obtained following oral administration of a 75-g glucose load during fasting.

Two-step screening included the obtaining of blood glucose levels following oral administration of 50-g glucose load in the non-fasting state. If positive, patients underwent a glucose-tolerance test with 100-g glucose load in the fasting state.

The primary outcomes sought by the investigators were diagnosis of gestational diabetes, large-for-gestational-age infants, a perinatal composite outcome, gestational hypertension or preeclampsia, and primary cesarean section.

As such, 66% and 92% of women in each group, respectively, adhered to their assigned screening

“Gestational diabetes was diagnosed in 16.5% of the women assigned to the one-step approach and in 8.5% of those assigned to the two-step approach (unadjusted relative risk, 1.94; 97.5% CI, 1.79-2.11),” indicated the investigators.

They also reported that large-for-gestational-age infants occurred in 8.9% in the one-step group and 9.2% in the two-step (relative risk, 0.95; 97.5% CI, 0.87-1.05).

Additionally, the perinatal composite outcome—which included stillbirth, neonatal death, shoulder dystocia, bone fracture, or any arm or hand nerve palsy related to birth injury—occurred in 3.1% for one-step and 3.0% and two-step (relative risk, 1.04; 97.5% CI, 0.88-1.23)

Gestational hypertension or preeclampsia occurred in 13.6% and 13.5% (relative risk, 1.00; 97.5% CI, 0.93-1.08) and primary cesarean section occurred in in 24.0% and 24.6% (relative risk, 0.98; 97.5% CI, 0.93-1.02).

Conclusion

Hillier and colleagues indicated that a lower adherence rate for the one-step approach was consistent with previous findings.

Nonetheless, they underscored the lack of differences in maternal and perinatal outcomes between methods—despite the increased diagnosed incidences with the fasting one-step approach, which has a notably lower diagnostic cut-off threshold.

They acknowledged various potential limitations with the study, including their hands-off approach following randomization and the providers’ awareness of patient screening assignments.

“This head-to-head design compared outcomes in a “real-world” clinical setting in which virtually the entire population at these trial sites was included, and we would expect results to be generalizable to similar settings,” they indicated. “Owing to the overall racial or ethnic makeup of these regions, Black and American Indian women were not well represented in the trial sample.”

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