Pediatric Inpatient Continuous Glucose Monitor Accuracy by Sensor Wear Day, Hospital Day, and Glucose Rate of Change

BACKGROUND: Continuous glucose monitoring (CGM) improves glycemic outcomes but inpatient use in the United States is not FDA approved, despite the potential need for frequent glycemic monitoring during hospitalization. We sought to assess CGM accuracy in the pediatric hospital setting and to evaluate the impact of potential modifiers of accuracy, including sensor wear day, hospitalization day, and glucose changes. METHODS: In this retrospective cross-sectional accuracy study among youth and young adults with diabetes hospitalized at two pediatric centers, reference point-of-care (POC) capillary glucose values were compared with Dexcom G7 CGM glucose readings (paired within 5 min). Accuracy was assessed using standard metrics, including mean absolute relative difference (MARD) and Parkes error grids, overall, and stratified by sensor wear day, hospital day, and CGM glucose rate of change. RESULTS: We analyzed 544 POC-CGM glucose pairs from 68 participants with diabetes aged 2-22 years (mean 12.4 ± 5.8 years old, 58.8% female, 66.2% White, 8.8% Hispanic) during 80 hospital encounters. The overall MARD was 12.5%. Accuracy was comparable on sensor wear day 1 and days 2-6 (MARD 12.3% vs 13.6%, respectively) and was best on wear days 7-10 (MARD 10.6%). Accuracy improved from hospital day 1 (MARD 13.7%) to hospital days 2-4 and 5-30 (MARD 10.4% and 12.5%, respectively). Overall and on wear day 1, almost all glucose pairs (99%) fell within low-risk Parkes error grid zones A and B. Accuracy was best with a flat [-1 to 1 mg/(dL·min)] rate of change (MARD 11.5%-11.9%) and was reduced with rapidly rising or falling [beyond -2 or 2 mg/(dL·min)] CGM values (MARD 16.6%-18.4%). CONCLUSIONS: In this pediatric hospital CGM accuracy study, MARD was within a favorable range of <14% overall and throughout sensor wear and hospitalization. Reduced accuracy with rapidly changing glucose highlights the need to incorporate trend arrows into hospital CGM protocols.