Continuous glucose monitoring reduces risk of large-for-gestational-age births in gestational diabetes

An international, multicenter randomized controlled trial has found that real-time continuous glucose monitoring (rt-CGM) lowered the proportion of large-for-gestational-age (LGA) births among women with gestational diabetes compared with self-monitoring of blood glucose (SMBG). The findings, published in The Lancet Diabetes & Endocrinology, provide new evidence to inform glucose monitoring approaches during pregnancy.^1,2

According to the Medical University of Vienna, the trial represents “the first multicenter randomized controlled trial to demonstrate the advantages of the digital method over conventional self-monitoring of blood glucose using finger pricks and opens up new perspectives for the targeted care of women with gestational diabetes.”

Study design and population

The open-label, parallel-group study recruited women aged 18 to 55 years with singleton gestations and gestational diabetes diagnosed according to International Association of the Diabetes and Pregnancy Study Groups criteria. Participants were enrolled at 4 university hospitals in Austria, Germany, and Switzerland. A total of 375 women were randomly assigned to rt-CGM (n=190) or SMBG (n=185), with randomization structured to balance gestational age at entry, prior gestational diabetes, and preconception body mass index.

Participants assigned to SMBG used blinded CGM for 10 days after randomization and again at 36 to 38 weeks’ gestation, while the rt-CGM group used open rt-CGM until delivery. All participants received standard gestational diabetes management according to clinical guidelines.

The mean gestational age at gestational diabetes diagnosis was 25.2 weeks (SD, 2.3), and the mean gestational age at randomization was 28.6 weeks (SD, 1.9).

Primary outcome: Large-for-gestational-age births

In the intention-to-treat population, LGA births occurred in 4% (6 of 170) of the rt-CGM group compared with 10% (18 of 175) of the SMBG group (OR, 0.32; 95% CI, 0.10–0.87; P = .014). The Medical University of Vienna noted that “only 4% of women in the rt-CGM group gave birth to an above-average weight child...compared with ten percent in the control group.” Average birthweight percentiles were also lower in the rt-CGM group.

Gestational diabetes is associated with an elevated risk of excessive fetal growth, which can lead to complications at birth and may influence future metabolic health. The Medical University of Vienna stated that early diagnosis and consistent treatment “can significantly reduce this risk.”

Additional neonatal outcomes

Rates of small-for-gestational-age (SGA) births were higher than expected in both groups: 19% in the rt-CGM group and 13% in the SMBG group (OR, 1.59; 95% CI, 0.86–2.99; P = .11). The research team noted that further study is needed to understand this pattern. Christian Göbl commented that “it was noticeable that in both study groups there were more newborns with below-average birth weight (small for gestational age, SGA). This could indicate that very strict sugar management could also influence the risk of insufficient foetal growth–and requires further investigation.”

Serious adverse events occurred in 12% of participants in the rt-CGM group and 15% of those in the SMBG group (OR, 0.77; 95% CI, 0.42–1.40; P = .39).

Implications for pregnancy care

The ability to monitor glucose continuously may support more precise glycemic management. As Göbl explained, “Continuous glucose monitoring via a sensor placed under the skin allows patients to check their blood sugar levels at any time. This enables them to make specific adjustments to their lifestyle or insulin therapy, which can have a positive impact on the course of their pregnancy.”

Tina Linder added that “our results suggest that real-time glucose monitoring systems can improve pregnancy care—especially for women who benefit from more intensive therapy,” while emphasizing that “the optimal blood glucose target values still need to be precisely defined in order to avoid both overgrowth and undergrowth of the foetus.”

Conclusion

In this multicenter randomized trial, rt-CGM use among women with gestational diabetes reduced the proportion of LGA births compared with SMBG, with no differences in serious adverse events. The higher prevalence of SGA births observed across both groups highlights the need for additional research to define glycemic targets that minimize risks at both extremes of fetal growth.

References

1. Linder T, Dressler-Steinbach I, Wegener S, et al; GRACE study collaborative group. Glycaemic control and pregnancy outcomes with real-time continuous glucose monitoring in gestational diabetes (GRACE): an open-label, multicentre, multinational, randomised controlled trial. The Lancet Diabetes Endocrinol. Published online November 24, 2025. doi:10.1016/S2213-8587(25)00288-8
2. Gestational diabetes: continuous glucose monitoring reduces risk of excessive birth weight. News release. Medical University of Vienna. December 4, 2025. Accessed December 4, 2025. https://www.eurekalert.org/news-releases/1108487