Clinical accuracy of Dexcom G6 and G7 continuous glucose monitors in hospitalized pediatric patients with type 1 diabetes: a real-world study

Purpose: Continuous glucose monitoring (CGM) is being increasingly utilized in inpatient pediatric diabetes care; however, data on its real-world accuracy remain limited. Methods: We retrospectively assessed the clinical accuracy of factory-calibrated Dexcom G6 and G7 CGM systems in 69 pediatric patients with type 1 diabetes at a Korean tertiary hospital between 2019 and 2025. A total of 1838 CGM readings were temporally paired with point-of-care (POC) capillary glucose measurements. Accuracy was evaluated using the mean absolute relative difference (MARD), mean absolute difference (MAD), Bland-Altman analysis, and Clarke error grid classification. Subgroup analyses were performed according to the sensor day, glucose range, care setting, and CGM type. Results: The overall MARD was 10.6±10.1% and MAD was 15.4±16.2 mg/dL. Accuracy improved over time, with MARD declining from 13.8% (G6) and 11.0% (G7) on Day 1 to <10% on Days 6 and 4, respectively. Bland-Altman limits narrowed from ±60 to ±39 mg/dL. During Days 6-11, 86% of CGM-POC pairs were within Clarke Zone A and 97% in Zones A+B. The MAD increased with higher glucose levels, whereas the MARD was highest during hypoglycemia (15.2%) and lowest during hyperglycemia (8.5%). ICU admission significantly increased the MAD (p=0.001) without affecting the MARD. G7 demonstrated superior accuracy to G6 (pooled MARD: 9.8% vs. 11.2%, p=0.003). Mixed-effects modeling confirmed that sensor day was an independent predictor of accuracy improvement (-0.34% MARD/d, p<0.001). Conclusion: The Dexcom G6 and G7 CGMs met the ISO 15197:2013 and FDA integrated-CGM criteria after a short inpatient stabilization period.