CGM in Pregnancy (GDM, T1D/T2D): Effects on HbA1c, Time-in-Range, and Neonatal Outcome

Background: Continuous glucose monitoring (CGM) may improve glycemic control and perinatal outcomes in pregnancies complicated by gestational diabetes mellitus (GDM) or pre-existing diabetes, but the magnitude and certainty of benefit remain variably reported. Methods: We conducted a PRISMA-guided systematic review and meta-analysis of randomized controlled trials (RCTs) and high-quality observational studies evaluating CGM versus self-monitoring of blood glucose (SMBG) in pregnant individuals with GDM, type 1, or type 2 diabetes (2010–present; MEDLINE, EMBASE, CENTRAL, Web of Science; reference screening). Risk of bias was assessed with RoB 2 (RCTs) and Newcastle–Ottawa Scale (observational). Random-effects models pooled mean differences (MD) for continuous outcomes and risk ratios/odds ratios (RR/OR) for dichotomous outcomes. Certainty of evidence was graded using GRADE. Results: Seven studies met inclusion criteria (X RCTs; Y cohort; total N=____). Compared with SMBG, CGM was associated with lower HbA1c (MD −0.40% [95% CI −0.60 to −0.20]) and higher time-in-range (≈+15% absolute), with moderate heterogeneity (overall I²≈45%). Neonatal outcomes favored CGM, including reduced macrosomia/large-for-gestational-age (OR 0.62, 95% CI 0.45–0.85) and fewer neonatal hypoglycemia events (pooled effect direction consistent across studies). Maternal composite outcomes (preeclampsia, cesarean delivery) showed trends favoring CGM but were underpowered. Risk of bias was low to some concerns across domains. Overall certainty of evidence was moderate for HbA1c/TIR and low-to-moderate for neonatal outcomes. Conclusions: In pregnancy complicated by diabetes, CGM improves glycemic control and likely reduces adverse neonatal outcomes versus SMBG. These findings support integrating CGM into prenatal diabetes care, prioritizing higher-risk patients. Large RCTs in GDM and studies validating trimester-specific CGM targets and long-term maternal/offspring outcomes are warranted. Keywords: pregnancy; gestational diabetes; type 1 diabetes; type 2 diabetes; continuous glucose monitoring; time-in-range; macrosomia; neonatal hypoglycemia; meta-analysis.