Continuous glucose monitoring versus blood glucose self-monitoring in patients with gestational diabetes mellitus managed via diet control: a prospective pilot study

Objectives: To compare agreement between continuous glucose monitoring (CGM) and self-monitoring of blood glucose and to assess the acceptance and satisfaction of CGM among Chinese women with gestational diabetes mellitus (GDM) in Hong Kong. Methods: Chinese women diagnosed with GDM after 28 weeks of gestation and managed via diet control were recruited at Kwong Wah Hospital, Hong Kong, between January 2025 and June 2025. Participants were instructed to wear a CGM sensor for 15 days. Additionally, they were instructed to perform self-monitoring of blood glucose via finger prick four times per day on 4 separate days. Fasting glucose levels in the morning and postprandial glucose levels 2 hours after each meal were recorded. Participants’ knowledge, application, usage, and acceptance and satisfaction of CGM were assessed using an 18-item questionnaire. Satisfaction with CGM was also assessed using the validated Chinese version of the Glucose Monitoring Satisfaction Survey. Results: In total, 50 Chinese women diagnosed with GDM after 28 weeks of gestation and managed via diet control were included in the analysis. A total of 711 paired measurements were collected. Agreement between CGM and self-monitoring measurements was good, with a concordance correlation coefficient of 0.836. The linear-mixed-effects-based Bland-Altman plot showed a mean bias between the two methods of 0.069 mmol/L. Deming regression yielded an intercept of -0.046‎ and a slope of 1.017‎, indicating minimal fixed and proportional bias‎‎. The mixed-effects model showed a precision ratio of 0.626. The mean absolute relative difference was 8.04%. Parkes error grid analysis indicated that 100% of paired measurements were in zone A or B. Overall, 83.7% were satisfied with CGM and accepted its use for glucose monitoring during pregnancy when the sensor was provided free of charge. Conclusion: Agreement between CGM and self-monitoring measurements was good in Chinese women with GDM. CGM can be used as an adjunct to self-monitoring with finger prick‎s, which should be performed at least weekly to cross-check agreement. Most women with GDM accepted and were satisfied with CGM.