Impact of Monitoring Modality on Glycemic Outcomes in Gestational Diabetes: CGM vs Capillary Testing

Can real-time continuous glucose monitoring (CGM) achieve higher percent glucose time in range (%TIR) vis-à-vis capillary blood glucose (CBG) monitoring among pregnant women with gestational diabetes (GDM)?

Researchers from the United States sought to answer this question in an open-label, single-center, randomized-controlled trial with pregnant women with ≥20 weeks' gestation and diagnosed with GDM between February 2021 and June 2023. The participants were randomized in a 2:1 ratio to either real-time CGM + adjunctive CBG monitoring (intervention group) or to CBG monitoring alone (control group). Participants in the intervention group were instructed to use the Dexcom G6 CGM system continuously from enrollment until hospital admission for delivery. The control group monitored glucose with CBG four times daily and additionally underwent blinded CGM approximately every 20 days during the study period. The percentage of time in range (TIR), from enrollment until hospitalization for delivery was the primary study outcome. Out of the 111 women enrolled for the study,  74 were assigned to the intervention group and 37 acted as controls.

Findings published in the journal Diabetes Care showed that the CGM group (93%) achieved a significantly higher %TIR, defined as 60–140 mg/dL,  compared to the control group (88%). The intervention group demonstrated significantly higher daytime TIR, along with lower 24-hour and daytime mean glucose levels, and a reduced percentage of time spent >140 mg/dL, secondary CGM metrics, compared with the control group.

This study showed that, in pregnant women with gestational diabetes, real-time CGM use led to a significant improvement in %TIR compared with the current approach of monitoring by CBG monitoring. But further studies are needed to assess its impact on perinatal and neonatal outcomes.

Reference

1.   Amy M Valent, et al. Real-time continuous glucose monitoring in pregnancies with gestational diabetes mellitus: a randomized controlled trial. Diabetes Care. 2025 Sep 1;48(9):1581-1588. doi: 10.2337/dc25-0115.