Observational Study
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World J Diabetes. Aug 15, 2025; 16(8): 106967
Published online Aug 15, 2025. doi: 10.4239/wjd.v16.i8.106967
Performance of flash continuous glucose monitoring and glycemic marker correlations in Chinese pregnant women with non-type 1 diabetes
Ling Lyu, Yi-Ling Huang, Yu Huang, Ze-Yu Wu, Fan Ping, Yu-Xiu Li
Ling Lyu, Yi-Ling Huang, Yu Huang, Ze-Yu Wu, Fan Ping, Yu-Xiu Li, Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
Co-corresponding authors: Fan Ping and Yu-Xiu Li.
Author contributions: Lyu L performed formal analysis, visualization, and wrote the original draft; Huang YL conducted the investigation; Huang YL, Huang Y, Wu ZY, Ping F, and Li YX participated in the review and editing of the manuscript; Lyu L and Wu ZY performed data curation; Huang Y supervised the study; Ping F and Li YX conceptualized the study, developed the methodology, acquired funding, they contributed equally to this article, they are the co-corresponding authors of this manuscript; and all authors thoroughly reviewed and endorsed the final manuscript.
Supported by the National High Level Hospital Clinical Research Funding, No. 2022-PUMCH-B-015; and the Healthcare Quality and Safety Incubation Program of Peking Union Medical Foundation, No. XHFY2406.
Institutional review board statement: This study was approved by the Medical Ethics Committee of Peking Union Medical College Hospital, approval No. I-24PJ2607.
Informed consent statement: All study participants, or their legal guardians, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Data sharing statement: Technical appendix, statistical code, and dataset are available from the corresponding author at pingfan@pumch.cn. Participants gave informed consent for data sharing.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Fan Ping, MD, Associate Professor, Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No. 1 Shuai-Fu-Yuan Street, Dongcheng District, Beijing 100730, China. pingfan@pumch.cn
Received: March 12, 2025
Revised: May 14, 2025
Accepted: June 30, 2025
Published online: August 15, 2025
Processing time: 155 Days and 21.7 Hours
Abstract
BACKGROUND

Maternal diabetes significantly increases the risk of adverse maternal and neonatal outcomes. Traditional self-monitoring of blood glucose is often invasive and limited in its ability to capture glycemic variability. Flash continuous glucose monitoring (FCGM) offers a promising alternative; however, its reliability and correlation with biochemical markers such as hemoglobin A1c (HbA1c) and glycated albumin (GA) in pregnant women with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) remain underexplored.

AIM

To evaluate the performance of the FreeStyle Libre H FCGM against plasma glucose and its correlations with HbA1c and GA.

METHODS

This prospective observational study involved 152 pregnant women with GDM or T2DM, with intermittent collection of venous plasma glucose, HbA1c, GA, and concurrent FCGM data at regular intervals at a single center. Relationships were evaluated using restricted cubic spline and mixed-effects models. Receiver operating characteristic curve analysis was performed to compare the ability of HbA1c and GA to detect suboptimal glycemic control.

RESULTS

Analysis of 507 FCGM-plasma glucose pairs revealed an overall mean absolute relative difference of 7.96%. Mean absolute relative differences were 9.22%, 7.75%, and 4.15% for low (3.5-4.4 mmol/L), medium (4.5-7.8 mmol/L), and high (7.9-13 mmol/L) glucose levels, respectively. Most values fell within zone A or zone B on the Clarke and Parkes Error Grids. Bland-Altman analysis indicated a slight underestimation by FCGM (-0.121 mmol/L). Restricted cubic spline analysis revealed significant linear or nonlinear associations between HbA1c/GA and mean glucose, time in range, time above range, and coefficient of variation, but not time below range. Both HbA1c and GA were influenced by gestational age and pregestational body mass index. Receiver operating characteristic analysis showed that HbA1c had comparable or superior performance to GA in detecting suboptimal glycemic control based on FCGM-derived thresholds.

CONCLUSION

The FCGM system served as a validated reference for evaluating glycemic markers in pregnant women with T2DM and GDM. HbA1c reliably assessed average glycemia, while GA provided complementary insight.

Keywords: Diabetes; Continuous glucose monitoring; Hemoglobin A1c; Glycated albumin; Pregnancy

Core Tip: This study demonstrates the reliability of the FreeStyle Libre H flash continuous glucose monitoring (FCGM) system in pregnant women with gestational diabetes mellitus and type 2 diabetes mellitus, showing a low mean absolute relative difference of 7.96% compared to venous plasma glucose. Hemoglobin A1c (HbA1c) and glycated albumin (GA) showed significant linear or non-linear associations with FCGM metrics, although both were influenced by gestational age and pregestational body mass index. In this study, FCGM served as a validated reference for evaluating HbA1c and GA. HbA1c remained a reliable marker, while GA provided supplementary value for comprehensive glycemic assessment.