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Hillier TA, Pedula KL, Ogasawara KK, et al. A Pragmatic, Randomized Clinical Trial of Gestational Diabetes Screening. N Engl J Med. 2021 Mar 11;384(10):895-904. doi: 10.1056/NEJMoa2026028. (Original study)
Abstract

BACKGROUND: Gestational diabetes mellitus is common and is associated with an increased risk of adverse maternal and perinatal outcomes. Although experts recommend universal screening for gestational diabetes, consensus is lacking about which of two recommended screening approaches should be used.

METHODS: We performed a pragmatic, randomized trial comparing one-step screening (i.e., a glucose-tolerance test in which the blood glucose level was obtained after the oral administration of a 75-g glucose load in the fasting state) with two-step screening (a glucose challenge test in which the blood glucose level was obtained after the oral administration of a 50-g glucose load in the nonfasting state, followed, if positive, by an oral glucose-tolerance test with a 100-g glucose load in the fasting state) in all pregnant women who received care in two health systems. Guidelines for the treatment of gestational diabetes were consistent with the two screening approaches. The primary outcomes were a diagnosis of gestational diabetes, large-for-gestational-age infants, a perinatal composite outcome (stillbirth, neonatal death, shoulder dystocia, bone fracture, or any arm or hand nerve palsy related to birth injury), gestational hypertension or preeclampsia, and primary cesarean section.

RESULTS: A total of 23,792 women underwent randomization; women with more than one pregnancy during the trial could have been assigned to more than one type of screening. A total of 66% of the women in the one-step group and 92% of those in the two-step group adhered to the 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% confidence interval [CI], 1.79 to 2.11). In intention-to-treat analyses, the respective incidences of the other primary outcomes were as follows: large-for-gestational-age infants, 8.9% and 9.2% (relative risk, 0.95; 97.5% CI, 0.87 to 1.05); perinatal composite outcome, 3.1% and 3.0% (relative risk, 1.04; 97.5% CI, 0.88 to 1.23); gestational hypertension or preeclampsia, 13.6% and 13.5% (relative risk, 1.00; 97.5% CI, 0.93 to 1.08); and primary cesarean section, 24.0% and 24.6% (relative risk, 0.98; 97.5% CI, 0.93 to 1.02). The results were materially unchanged in intention-to-treat analyses with inverse probability weighting to account for differential adherence to the screening approaches.

CONCLUSIONS: Despite more diagnoses of gestational diabetes with the one-step approach than with the two-step approach, there were no significant between-group differences in the risks of the primary outcomes relating to perinatal and maternal complications. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ScreenR2GDM ClinicalTrials.gov number, NCT02266758.).

Ratings
Discipline Area Score
Family Medicine (FM)/General Practice (GP) 6 / 7
General Internal Medicine-Primary Care(US) 6 / 7
Endocrine 6 / 7
Obstetrics 6 / 7
FM/GP/Obstetrics 6 / 7
Internal Medicine 5 / 7
Comments from MORE raters

Endocrine rater

This large, well-conducted trial provides support against adopting the more cumbersome 1-step approach to diagnosing GDM. The fact that outcomes were similar between the 2 groups is not surprising as they were both offered treatment for GDM. It would be more useful to know whether there was a difference in complications between those diagnosed with the 1-step and treated and those who were undiagnosed (and therefore missed).

Endocrine rater

Controversies between the 1- and 2-step diagnostic approaches to diagnosing GDM have existed since the IADPSG recommended the 1-step approach. This real-world study is the first to evaluate any clinical differences in outcomes between the 2 ways to diagnose GDM. It shows no differences suggesting that the easier 2-step approach, although identifying fewer cases of GDM, could remain the way to go.

Family Medicine (FM)/General Practice (GP) rater

Gestational diabetes (GD) has become a 'growth area' of maternity care. Over-diagnosis is an issue with many screening programs. This large head-to-head RCT shows almost double the rate of giving women a diagnosis of GD with the one-step screening, with no improvement in outcome for all the extra women treated for the condition. This strongly suggests that one-stage screening is leading to over-diagnosis of milder GD. Higher participation rates in the two-stage screening are important, and may explain part of the equivalence in pregnancy outcomes despite lower detection rates of GD.

FM/GP/Obstetrics rater

This well done paper is not terribly helpful in helping to decide which of the 2 screening methods to use. It's difficult to extrapolate to our diverse population as the study population was so homogeneous (well off and 55% white). It's outside my ability to extrapolate guideline conclusions.

General Internal Medicine-Primary Care(US) rater

Important information for primary care physicians who provide prenatal care. Should change clinical practice.

Internal Medicine rater

May be relevant to use one-step as more studies are showing effects on kids later in life based on maternal weight and risks (even though this increases number of diagnoses of gestational DM).

Obstetrics rater

Critically important information as to the best and easiest way to screen for gestational diabetes for both the patient and provider.
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