Flash Glucose Measurements in Children with Type 1 Diabetes in Real-Life Settings: To Trust or Not to Trust?

Abstract

Background and Aims:

To evaluate the clinical accuracy of a flash glucose monitoring device FreeStyle Libre (FSL) among children with type 1 diabetes in real-world settings during a summer camp.

Materials and Methods:

During a summer camp, children with type 1 diabetes (n = 79, aged 8–18 years) were provided with FSLs for 12 days. On days 3, 7, and 11 of the study, they underwent supervised glucose testing at 8 timepoints. Glycemia was estimated by using FSL and measured with a personal glucometer within a period of 2 min. The glucose trend arrows were recorded.

Results:

The study was completed by 78 children (median: age 12.8 years, diabetes duration 5.8 years, HbA1c 58.5 mmol/mol). Mean absolute relative difference (MARD) between the FSL and the glucometer was 13.5% ± 12.9%. FSL was the most accurate in stable glycemic conditions: MARD 11.4% ± 10.4%, less accurate when glycemia was falling >2 mg/(dL·min) [0.111 mmol/(L·min)—MARD 22.6% ± 18.6%; P < 0.001 vs. stable conditions] and when the device could not determine the glucose trends (16.5% ± 16.3%, P = 0.01 vs. stable conditions). The FSL demonstrated lower accuracy during the day than the night [MARD 14.9% ± 14% vs. 11.2% ± 10.6%, P < 0.0001]. Out of 1655 data pairs of glucometer and FSL, using the Surveillance Error Grid methodology we determined that 80.36% of FSL readings were associated with no clinical risk, 18.73% with slight risk and only one high-risk measurement was detected.

Conclusion:

FSL is accurate in children, but its accuracy depends on the glucose trend. Results flagged by the rapid fall flag and “trend undetermined” should be verified by blood glucose measurements.