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

Abstract

Objective

Continuous glucose monitoring is recommended for pregnant women with type 1 diabetes, due to associations with decreased hemoglobin A1c and large for gestational age. However, its benefit in type 2 diabetes and gestational diabetes is not established. This systematic review and meta-analysis compared usage of continuous glucose monitoring to self-monitoring of blood glucose both across and within diabetes in pregnancy and determined which glucose metrics are associated with perinatal outcomes, to potentially inform treatment targets in diabetes in pregnancy.

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 continuous glucose monitoring with self-monitoring of blood glucose in diabetes in pregnancy were included.

Study appraisal and synthesis methods

Randomized controlled trials and quasi-experimental studies were analyzed separately. Data were extracted on continuous glucose monitoring metrics, hemoglobin A1c, rates of cesarean delivery, large for gestational age, small for gestational age, neonatal hypoglycemia, and neonatal intensive care unit admission, summarized as mean differences or odds ratios with 95% confidence intervals and 95% prediction intervals. Prespecified subgroup analyses were undertaken by diabetes in pregnancy subtype, including duration of continuous glucose monitoring use (continuous vs intermittent) for large for gestational age. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations framework.

Results

Across diabetes in pregnancy, continuous glucose monitoring (vs self-monitoring of blood glucose) decreased hemoglobin A1c (mean difference, −0.22% [95% confidence interval, −0.37, −0.08]) (7 randomized controlled trials, moderate-certainty evidence). Within diabetes in pregnancy, continuous glucose monitoring use (vs self-monitoring of blood glucose) showed similar but stronger benefits in both type 1 diabetes when used throughout pregnancy (hemoglobin A1c mean difference, −0.18% [95% confidence interval, −0.36, 0.00]; large for gestational age odds ratio, 0.51 [0.28, 0.90]) (1 randomized controlled trial, high-certainty evidence), and gestational diabetes when used intermittently (hemoglobin A1c mean difference, −0.18 [95% confidence interval, −0.33, −0.02]) (5 randomized controlled trials, moderate-certainty evidence) and large for gestational age (odds ratio, 0.46 [0.26, 0.81]) (1 quasi-experimental study, low-certainty evidence), with insufficient data for continuous glucose monitoring benefit in type 2 diabetes. Increased pregnancy %time-in-range (type 1 diabetes) and decreased mean sensor glucose (type 1 diabetes/gestational diabetes) were associated with decreased large for gestational age.

Conclusion

Usage of continuous glucose monitoring (vs self-monitoring of blood glucose) reduces hemoglobin A1c and possibly large for gestational age across diabetes in pregnancy. Greatest benefit was evidenced in type 1 diabetes, followed by gestational diabetes, although continuous glucose monitoring duration differed. Mean sensor glucose and pregnancy %time-in-range are important continuous glucose monitoring metrics for reducing large for gestational age.