The impact of continuous glucose monitoring on glycated hemoglobin in pregnant women with type 1 diabetes: an integrative review

Abstract

Background: Pregnancy in women with type 1 diabetes (T1D) is associated with increased risk of adverse outcomes, including preeclampsia and macrosomia. Normalizing glycated hemoglobin (A1C) helps minimize these risks. Previous evidence suggests that continuous glucose monitoring (CGM) improves treatment decisions and glycemic control. However, no synthesized evidence currently assesses whether CGM use is associated with improved A1C levels in this population. Objective: The aim of this integrative review is to compare A1C levels during pregnancy between women with T1D who use CGM and those who do not use CGM (e.g. intermittent blood glucose monitoring only). Methods: An integrative review was conducted in accordance with Whittemore and Knafl’s guidelines. Three databases (CINAHL, PubMed, and Web of Science) were searched on 5 June 2024. Studies were included if they involved pregnant women with T1D and reported pregnancy A1C levels for both CGM users and non-users, enabling pooled analysis using sample size as a weighting factor. Study quality was assessed using the Mixed Methods Appraisal Tool (version 2018). Results: Of 300 screened articles, nine met the inclusion criteria. CGM users consistently demonstrated lower pooled mean A1C levels than non-users across all trimesters: first trimester (6.55% vs. 6.82%; SD = 0.72 vs. 0.93), second trimester (5.89% vs. 6.11%; SD = 0.55 vs. 0.63), and third trimester (6.07% vs. 6.24%; SD = 0.53 vs. 0.61). Overall, CGM users had a lower average pooled mean A1C throughout pregnancy (6.19% vs. 6.40%; SD = 0.61 vs. 0.74). Conclusions: CGM use in pregnant women with T1D may support better glycemic target achievement by providing real-time glucose data that informs insulin dosing and dietary adjustment. These findings support further investigation in larger controlled studies.