Evidence for improved glucose metrics and perinatal outcomes with continuous glucose monitoring compared to self-monitoring in diabetes during pregnancy.

OBJECTIVE Continuous glucose monitoring (CGM) is recommended for pregnant women with type 1 diabetes (T1D), due to associations with decreased HbA1c and large-for-gestational age (LGA). However, its benefit in type 2 diabetes (T2D) and gestational diabetes (GDM) is not established. This systematic review and meta-analysis compared usage of CGM to self-monitoring of blood glucose (SMBG) both across and within diabetes in pregnancy (DIP), and determined which glucose metrics are associated with perinatal outcomes, to potentially inform treatment targets in DIP. DATA SOURCES We searched Medline, Embase, CENTRAL, CINAHL and Scopus, from January 2003 to August 2024. STUDY ELIGIBILITY CRITERIA Randomized controlled trials and quasi-experimental studies comparing CGM with SMBG in DIP were included. STUDY APPRAISAL AND SYNTHESIS METHODS RCTs and quasi-experimental studies were analyzed separately. Data were extracted on CGM glucose metrics, HbA1c, rates of cesarean delivery, LGA, small-for-gestational age (SGA), neonatal hypoglycemia and neonatal intensive care unit (NICU) admission, summarized as mean differences (MD) or odds ratios (OR) with 95% Confidence Intervals (95%CI) and 95% Prediction Intervals (95%PI). Prespecified subgroup analyses were undertaken by DIP subtype, including duration of CGM use (continuous vs intermittent) for LGA. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework. RESULTS Across DIP, CGM (vs SMBG) decreased HbA1c (MD -0.22% [95%CI: -0.37, -0.08]) (7 RCTs, moderate-certainty evidence). Within DIP, CGM use (vs SMBG) showed similar but stronger benefits in both T1D when used throughout pregnancy (HbA1c MD -0.18% [95%CI: -0.36, 0.00], LGA OR 0.51 [0.28, 0.90]) (1 RCT, high-certainty evidence), and GDM when used intermittently (HbA1c MD -0.18 [95%CI: -0.33, -0.02]) (5 RCTs, moderate-certainty evidence) and LGA (OR 0.46 [0.26, 0.81]) (1 quasi-experimental study, low-certainty evidence), with insufficient data for CGM benefit in T2D. Increased pregnancy %time-in-range (T1D) and decreased mean sensor glucose (T1D/GDM) were associated with decreased LGA. CONCLUSIONS Usage of CGM (vs SMBG) reduces HbA1c and possibly LGA across DIP. Greatest benefit was evidenced in T1D, followed by GDM, although CGM duration differed. Mean sensor glucose and pregnancy %time-in-range are important CGM metrics for reducing LGA.