medwireNews: Women with gestational diabetes have similar perinatal and neonatal outcomes regardless of whether they use real-time continuous glucose monitoring (rtCGM) or self-monitoring of blood glucose (SMBG), Swiss study findings indicate.
Although there was no significant glucose control benefit of using rtCGM over SMBG, Sofia Amylidi-Mohr (Inselspital University Hospital of Bern) and co-authors say that “rtCGM might offer a valuable alternative to finger-prick testing without compromising pregnancy outcomes,” particularly as study participants expressed a stronger preference for an automated device.
Between September 2021 and June 2024, Amylidi-Mohr and team randomly assigned 299 pregnant women (mean age 33 years) with gestational diabetes to measure their blood glucose levels via rtCGM (n=156) or SMBG (n=143). The women were diagnosed with gestational diabetes between 24 and 28 weeks of gestation, had a glycated hemoglobin level below 6.5% (48 mmol/mol; mean 5.0%, 31 mmol/mol) and a mean BMI of 25.7 kg/m2.
Those randomly assigned to use rtCGM had a glucose target of 3.5–7.8 mmol/L (63.1–140.6 mg/dL), while the participants using SMBG tested six times daily, with fasting and preprandial targets of 5.3 mmol/L (95.6 mg/dL) or less, and a 1-hr postprandial target of 8.0 mmol/L (144.2 mg/dL) or less, respectively. They were given insulin therapy if rtCGM time in range was below 85%, or if 15% of SMBG results were above target over 2 weeks.
The researchers report in The Lancet Diabetes & Endocrinology, that there was no significant difference between the women using rtCGM and SMBG in the rates of large for gestational age infants (10 vs 10%), macrosomia (6 vs 3%), polyhydramnios (27 vs 24%), neonatal hypoglycemia (6 vs 6%), and stillbirth (0 vs 0%).
When these outcomes were analyzed together as a primary composite outcome, the rates in the rtCGM and SMBG groups were a comparable 36% and 35%, respectively.
Among the secondary outcomes, there were no significant differences with rtCGM versus SMBG in gestational weight gain (mean 12.1 vs 11.7 kg), and in the rates of pre-eclampsia (5 vs 3%), fetal growth restriction (7 vs 7%), spontaneous premature birth (3 vs 1%), induction of labor (38 vs 45%), cesarean section (41 vs 43%), neonatal intensive care unit admission (3 vs 3%), and need for neonatal respiratory support (6 vs 2%).
However, time in glycemic range during later pregnancy was significantly lower with rtCGM than with SMBG, at 92.2% versus 96.9%, and while the proportion of patients prescribed insulin was numerically higher at 55.0% versus 45.0%, the rtCGM group did start insulin significantly later on average (30.6 vs 31.8 weeks).
The only adverse events were skin irritation, which occurred in six (4%) participants in the rtCGM intervention group and in one (<1%) participant in the SMBG control group, and a questionnaire on patient preference revealed that in both groups, the women would have used rtCGM over SMBG if they had the choice.
Amylidi-Mohr and co-authors conclude: “Our results show that the outcome in individuals with gestational diabetes is not improved by the use of rtCGM.”
However, they add that “rtCGM seems to be more acceptable among pregnant women and could be useful in cases of non-adherence or to ease gestational diabetes management.”
In an accompanying comment David Simmons (Western Sydney University, New South Wales, Australia) and Thora Chai (University of Sydney, New South Wales, Australia) say the study shows that “excellent glycaemic metrics can be achieved in a relatively low-risk gestational diabetes population with SMBG alone, even compared with a time in range target of 85% (conventionally currently recommended to be 70%).”
However, they point out that “the overall study cohort was considered to be at relatively low risk of adverse pregnancy outcomes” and “it is unclear whether the same would be true for more complex groups, including those with greater obesity or early gestational diabetes.”
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Lancet Diabetes Endocrinol 2025; doi: 10.1016/S2213-8587(25)00063-4
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