Continuous Glucose Monitoring in Gestational Diabetes: Insights from the DipGluMo Randomized Controlled Trial in Switzerland

Highlights

• In a randomized controlled trial of 299 women with gestational diabetes, real-time continuous glucose monitoring (rtCGM) did not improve a composite of perinatal outcomes compared to self-monitoring of blood glucose (SMBG).
• Patient preference for rtCGM was significantly higher than for SMBG, suggesting benefits in treatment satisfaction and convenience.
• Adverse events were minimal and predominantly limited to mild skin reactions in the rtCGM group.
• The study is the first adequately powered RCT to address the efficacy of rtCGM versus SMBG in gestational diabetes for pregnancy outcomes.

Study Background and Disease Burden

Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy, affecting up to 10% of pregnancies worldwide. It is associated with increased risks of maternal and neonatal morbidity, including preeclampsia, macrosomia, neonatal hypoglycemia, and stillbirth. Achieving optimal glycaemic control is paramount in mitigating these adverse outcomes. Self-monitoring of blood glucose (SMBG) has long been the standard of care, but it is burdensome and relies on patient adherence. Real-time continuous glucose monitoring (rtCGM) offers the potential for improved glycaemic surveillance, prompt feedback, and reduced burden, but its clinical impact on pregnancy outcomes in GDM remains uncertain. The DipGluMo trial addresses this critical evidence gap by directly comparing rtCGM and SMBG in a contemporary Swiss cohort.

Study Design

The DipGluMo study was an open-label, single-centre, randomized, controlled trial conducted at a university hospital in Bern, Switzerland. Pregnant individuals aged 18-45 years diagnosed with GDM according to the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria were eligible. Participants were randomized 1:1 to either an rtCGM intervention group or a control group using SMBG. Central randomization accounted for key prognostic variables including pre-pregnancy BMI, previous GDM, family history of type 2 diabetes, and ethnicity. The primary endpoint was a composite of clinically meaningful perinatal outcomes: large-for-gestational-age (LGA) infants, macrosomia, polyhydramnios, neonatal hypoglycemia, and stillbirth. Key secondary outcomes included patient preference and maternal glycaemic control metrics. The primary analysis followed the intention-to-treat principle, enhancing internal validity.

Key Findings

Between September 29, 2021, and June 11, 2024, 302 pregnant women with GDM were enrolled; 156 were assigned to the rtCGM group and 143 to the SMBG group completed the study, with primary outcome data available for 297 (99%) of 299 participants. The composite primary outcome occurred at similar rates in both groups (odds ratio 1.02; 95% confidence interval [CI], 0.63–1.66), indicating no statistically significant difference in the frequency of adverse perinatal outcomes between rtCGM and SMBG.

Secondary outcomes revealed a notable patient preference for rtCGM. Participants reported greater satisfaction and found rtCGM more convenient than SMBG, which may translate to improved patient engagement and quality of life, although this did not manifest in improved clinical endpoints. Maternal glycaemic control parameters and adverse events were also assessed: mild skin reactions (mainly irritation at the sensor site) were more frequent in the rtCGM group (4%) than in the SMBG group (<1%), but no serious adverse events or device-related complications were reported. Importantly, the open-label design could have influenced subjective outcomes such as patient preference.

Table: Summary of Main Outcomes
| Outcome | rtCGM (n=156) | SMBG (n=143) | Odds Ratio (95% CI) |
|————————————-|——————–|——————|———————-|
| Composite perinatal outcome | Similar | Similar | 1.02 (0.63–1.66) |
| Device-related skin reactions | 6 (4%) | 1 (<1%) | — |
| Patient preference (higher rating) | Yes | No | — |

Expert Commentary

This trial is a significant contribution to the evidence base for diabetes technology in pregnancy. While rtCGM did not confer measurable clinical benefit for perinatal outcomes compared to SMBG, the device was strongly favored by patients for ease of use and comfort. Prior studies in type 1 diabetes and in non-pregnant populations have shown that rtCGM improves glycaemic control and reduces hypoglycemia (Battelino et al., 2019; Feig et al., 2017), but the translation of these benefits to gestational diabetes has remained unproven. The DipGluMo trial’s robust design and careful adjustment for confounders strengthen its conclusions.

Nevertheless, there are limitations. The single-centre Swiss cohort may limit generalizability, especially to settings with different baseline risks or health system infrastructure. The open-label nature is unavoidable due to the intervention but may influence subjective endpoints. Finally, the study was not powered to detect differences in individual rare outcomes such as stillbirth.

Guidelines from the American Diabetes Association and International Federation of Gynecology and Obstetrics currently recommend SMBG as standard for GDM, with a cautious approach to technology adoption pending further evidence (ADA, 2024; Hod et al., 2015). The present results support this cautious stance, but highlight an important role for patient-centered care: if a woman with GDM prefers rtCGM and is willing to accept the additional cost (and mild skin reactions), it may be reasonable to offer this option to support adherence and patient satisfaction. Cost-effectiveness analyses, as suggested by the authors, are warranted to clarify resource implications.

Conclusion

The DipGluMo trial demonstrates that real-time continuous glucose monitoring does not improve perinatal outcomes compared to self-monitoring in women with gestational diabetes, but is preferred by patients for its ease and convenience. While routine use of rtCGM cannot be recommended solely for clinical outcome improvement, its incorporation into individualized care may benefit select patients. Further research should focus on cost-effectiveness, long-term outcomes, and potential benefits in high-risk subgroups.

References

1. Amylidi-Mohr S, Zennaro G, Schneider S, Raio L, Mosimann B, Surbek D. Continuous glucose monitoring in the management of gestational diabetes in Switzerland (DipGluMo): an open-label, single-centre, randomised, controlled trial. Lancet Diabetes Endocrinol. 2025 Jul;13(7):591-599. doi: 10.1016/S2213-8587(25)00063-4.
2. Battelino T, Danne T, Bergenstal RM, et al. Clinical targets for continuous glucose monitoring data interpretation: Recommendations from the international consensus on time in range. Diabetes Care. 2019;42(8):1593-1603.
3. Feig DS, Donovan LE, Corcoy R, et al. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Lancet. 2017;390(10110):2347-2359.
4. American Diabetes Association. Standards of Medical Care in Diabetes—2024. Diabetes Care. 2024;47(Suppl 1):S237-S251.
5. Hod M, Kapur A, Sacks DA, et al. The International Federation of Gynecology and Obstetrics (FIGO) Initiative on gestational diabetes mellitus: A pragmatic guide for diagnosis, management, and care. Int J Gynaecol Obstet. 2015;131(Suppl 3):S173-S211.