BACKGROUND: In gestational diabetes, one of the key factors affecting perinatal outcomes is glycaemic control. We aimed to investigate the effect of real-time continuous glucose monitoring (rtCGM) on perinatal outcomes versus self-monitoring of blood glucose (SMBG).

METHODS: In this open-label, randomised, controlled trial, we recruited pregnant individuals aged 18-45 years with gestational diabetes, according to the International Association of Diabetes and Pregnancy Study Groups criteria, from a university hospital in Bern, Switzerland. Participants were randomly assigned (1:1) to the rtCGM intervention group or the SMBG control group. Randomisation was done centrally on the basis of pre-pregnancy BMI, previous gestational diabetes, family history of type 2 diabetes, and ethnicity. The primary endpoint was a composite of perinatal outcomes: large for gestational age, macrosomia, polyhydramnios, neonatal hypoglycaemia, and stillbirth. Key secondary outcomes were patient preference and maternal glycaemic control. Analyses were conducted on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT05037526.

FINDINGS: Between Sept 29, 2021, and June 11, 2024, 302 pregnant women with gestational diabetes were included in the study and randomly assigned to one of the groups. 156 participants were assigned to the rtCGM intervention group and 143 were assigned to the SMBG control group completed the study. Primary outcome data were available for 297 (99%) of 299 participants. The composite outcome did not differ significantly between the two groups (odds ratio 1·02 [95% CI 0·63-1·66]). The only adverse events were skin changes, occurring in six (4%) participants in the rtCGM intervention group and in one (<1%) participant in the SMBG control group (blinded device).

INTERPRETATION: Our results show that the outcome in individuals with gestational diabetes is not improved by the use of rtCGM. However, individuals expressed a higher preference for the rtCGM device. This finding suggests that rtCGM could be offered to simplify the management of gestational diabetes. A cost-effectiveness study could address what method requires fewer resources. To our knowledge, this is the first randomised trial powered to evaluate the efficacy of rtCGM regarding pregnancy outcomes.

FUNDING: The University of Bern and the Swiss Diabetes Foundation.

TRANSLATION: For the German translation of the abstract see Supplementary Materials section.

Obstetrics rater

Good blood sugar control is fundamental in treating gestational diabetes. This RCT showed no difference in composite outcome (e.g., macrosomia, neonatal hypoglycemia) for GDM compared with real-time continuous glucose monitoring (rtCGM) and intermittent self-monitoring and patient preference for rtCGM. There was a non-significant trend to more time with glucose in range with rtCGM, but both groups had good control and a low occurrence of adverse events. This may not be applicable to our usual GDM patients. The authors used the one-stage screen that is common in Europe but makes the diagnosis of GDM (many of whom will have milder disease) twice as likely as the two-step screen used in Canada. Also, the participants had low glucose at entry with a required HbA1C < 6.5, so would have a low occurrence of adverse GDM outcomes. RtCGM costs more (Cost Utility... J Comp Eff Res; 2023) but is preferred by patients, which may give better compliance with necessary sugar control in GDM.