Two-step screening may be best for gestational diabetes
medwireNews: Single-step screening for gestational diabetes makes twice the number of diagnoses of the two-step approach without resulting in better outcomes for women and infants, shows the randomized ScreenR2GDM trial.
The one-step approach, as recommended by the International Association of the Diabetes and Pregnancy Study Groups (IADPSG), was based on a single 2-hour fasting oral glucose tolerance test (OGTT). The two-step approach comprised a 1-hour nonfasting OGTT followed by a confirmatory 3-hour fasting OGTT for women with an intermediate glucose level of at least 130–140 mg/dL (7.2–7.8 mmol/L, depending on the study site) but below 200 mg/dL (11.1 mmol/L).
As reported in The New England Journal of Medicine, 23,792 pregnant women were randomly assigned to undergo one-step or two-step screening in a pragmatic, nonblinded trial.
Of these women, 66% and 92%, respectively, underwent the assigned approach; the researchers attribute this imbalance to providers’ “efforts to ensure screening by conducting the nonfasting two-step glucose challenge test at a prenatal visit.”
The one-step approach resulted in 16.5% of women receiving a gestational diabetes diagnosis, significantly more than the 8.5% who were diagnosed as such with the two-step approach, report Teresa Hillier (Kaiser Permanente Northwest, Portland, Oregon, USA) and study co-authors.
Despite this, there were no significant differences between the groups for the other primary outcomes. Specifically, 8.9% versus 9.2% of the one-step and two-step groups, respectively, had infants that were large for gestational age, and 3.1% and 3.0% had adverse perinatal outcomes such as stillbirth, neonatal death, and birth-related injuries.
A corresponding 13.6% and 13.5% had gestational hypertension or preeclampsia, while 24.0% and 24.6% of the one-step and two-step groups, respectively, required cesarean section.
The need for insulin or oral hypoglycemic treatment during pregnancy was similar in both groups, at 42.6% for women in the one-step group and 45.6% for those in the two-step group.
Writing in a linked editorial, Brian Casey (University of Alabama, Birmingham, USA) says the trial “provides robust evidence” that the single-step approach “resulted in the detection of gestational diabetes in almost one in five pregnant women, with no apparent maternal or perinatal benefit overall.”
He notes that “the potential long-term benefits of increased diagnoses of gestational diabetes – such as the identification of more women at high risk for subsequent diabetes who might benefit from risk-reduction strategies – were not addressed by the trial.”
Nevertheless, Casey concludes that “the perinatal benefits of the diagnosis of gestational diabetes with the use of the IADPSG single-step approach appear to be insufficient to justify the associated patient and health care costs of broadening the diagnosis.”
He adds: “Refocusing attention on interventions in women who are at risk for the development of diabetes is more likely to yield substantive benefits.”
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