Call for gestational diabetes testing to be reviewed

Ongoing concerns expressed by many doctors about the introduction of a one-step approach to the diagnosis of gestational diabetes mellitus (GDM) has led to a call for a review of the Australian diagnostic criteria from the authors of a Perspective published in the Medical Journal of Australia.

The International Association of the Diabetes and Pregnancy Study Groups' (IADPSG) one-step criteria has been recommended ahead of the Carpenter–Coustan two-step diagnostic criteria by the Australasian Diabetes in Pregnancy Society.

The Royal Australian College of General Practitioners (RACGP) and a National Institutes of Health (US) consensus panel objected to the adoption of the one-step process because "there is a lack of evidence that the subset of women who are identified by the one-step approach but who would have been considered normal by the two-step approach benefit from the increased monitoring and interventions involved with the diagnosis."

Professor Jenny Doust, Professor of Clinical Epidemiology at the University of Queensland, and colleagues now say a 2021 trial conducted in the US has validated the concerns of the RACGP and NIH, and have called for a review.

"Although the number of women diagnosed with GDM about doubled using the one-step approach rather than the two-step approach, no health benefits were seen for either the mother or the infants in this trial," Doust and colleagues wrote.

"A significant proportion of the women who were assigned to the one-step arm of the trial underwent a two-step process. This reflects the real-world preferences of the women and clinicians who participated in the trial.

"If the new GDM criteria include women with milder disease in the disease definition, these women will add to the number of women diagnosed but not to the number of women or infants with adverse outcomes, making it appear artificially as if results have improved."

The authors also pointed out that the US trial's results were consistent with an Australian observational study "that showed no benefit after the introduction of the one-step approach."

"The widened definition also involves considerable potential for harm, including life disruptions for the women diagnosed, psychosocial burdens, a risk of more invasive forms of delivery in these women, and potential harms to the infant from restricted diets and the use of insulin, including an increased risk of neonatal hypoglycemia," Doust and colleagues wrote.

"The one-step approach also involves increased costs and poor targeting of resources."

They concluded that:

"The new criteria were introduced without evidence of benefit, with significant risks of harms and considerable burdens to women and health care systems.

"About 25% of pregnancies diagnosed with gestational diabetes in Australia are affected by this change in the diagnostic criteria.

"We believe that the results of the American trial require an urgent need to revisit the diagnostic criteria used for GDM in Australia."