Latest generation of FreeStyle Libre (FSL) has been recently approved by FDA as equivalent to glucose meters for making therapeutic decisions. However, real-life evidence for this equivalence is needed.
Adolescents with type 1 diabetes (N=58) taking part in a summer camp were invited into the prospective observational study. For 14 days, they used FSL participating in camp activities. During four consecutive days, an 8-point glucose profile was collected. Capillary blood glucose (BG) were measured using Contour Plus One glucose meter and followed within 1 minute by FSL scan. Glucose trends arrows were also recorded. Accuracy of the system was assessed by calculation of bias and mean absolute relative difference (MARD), while clinical utility was checked against surveillance error grid (SEG).
Mean age equaled 13.8 years, (95%CI:13.2–14.3), diabetes duration 7.9 years (6.5-9.4), HbA1c 7.5% (7.2-7.8%). Altogether we were able to collect 1796 valid pairs of measurements of FSL and BG (median 32/patient). FSL overestimated BG by a mean of 6.5mg/dl (5.5-7.6) and overall MARD was 11.3% (10.8-11.8). SEG classified 97.5% of scans as clinically accurate (class A:85.3%, B:12.2%) and 2.5% as class C. FGM presented significantly worse MARD during rapid glucose decrease [17.9% (16.0-19.7) vs 10.2% (9.5-10.8), p<0.0001), during mountain hikes (16.6% (12.3-20.8) vs 11.1% (10.6-11.6), p=0.0131] and in children who presented adverse skin reactions to the sensor (13.5% (11.3-15.6) vs 11.1% (10.6-11.6), p=0.0381).
The new generation of FSL demonstrated good agreement with point-of-care BG measurements in real-life conditions. However, in some scenarios additional verification of measurements might be advised.