Continuous glucose monitoring for gestational diabetes

What does the evidence say about continuous glucose monitor for gestational diabetes during pregnancy?

1. CDC explains that CGMs sample glucose in interstitial fluid under the skin, not directly in blood. Interstitial and fingerstick values can differ, so occasional fingerstick checks remain important, especially for new users and when accuracy is uncertain. 1
2. FDA advises confirming a CGM value with a fingerstick meter when symptoms do not match the display and consulting the clinician before changing pump settings. The safety principle also applies when a sensor value seems inconsistent with the clinical situation. 2
3. WHO's 2025 pregnancy-diabetes guideline recommends self-monitoring of blood glucose for gestational diabetes and does not routinely recommend CGM for GDM or type 2 diabetes. It notes possible use in selected patients, including some who use insulin, where resources and expertise allow. 3
4. The GRACE trial, published in January 2026, randomized 375 patients across four European hospitals. Among those with primary-outcome data, large-for-gestational-age birth occurred in 6 of 170 CGM participants versus 18 of 175 fingerstick participants. The trial was open label and industry funded; the high overall frequency of small-for-gestational-age birth warrants further research. 4
5. The 2025 DipGluMo trial enrolled 302 patients at one Swiss center and found no significant difference in its composite perinatal outcome with CGM versus fingersticks (odds ratio 1.02, 95% confidence interval 0.63 to 1.66). This endpoint and study design differed from GRACE, so the results should be compared without assuming a universal benefit or no benefit. 5

Is continuous glucose monitor for gestational diabetes safe in each trimester?

• First trimester. If glucose concerns arise early, clarify whether the issue is preexisting diabetes, early abnormal glucose metabolism, or later gestational diabetes risk. CGM data should be interpreted with laboratory testing and the prenatal diabetes team, not used to classify the condition alone.
• Second trimester. Gestational diabetes screening usually occurs at 24 to 28 weeks. If CGM is added after confirmation, agree on pregnancy-specific targets, when fingersticks are still required, how meals are logged, and which trends should be reported.
• Third trimester. Insulin resistance and medication needs can change late in pregnancy. Sensor compression, site problems, rapid glucose changes, and interstitial-to-blood differences can produce confusing readings, so confirm discordant values and avoid self-directed medicine changes.