FreeStyle Libre and Dexcom G4 Platinum sensors: Accuracy comparisons during two weeks of home use and use during experimentally induced glucose excursions

This study compared the accuracy of the FreeStyle Libre (Abbott, Alameda, CA) and Dexcom G4 Platinum (DG4P, Dexcom, San Diego, CA) CGM sensors. Twenty-two adults with type 1 diabetes wore the two sensors simultaneously for 2 weeks. Libre was used according to manufacturer-specified lifetime (MSL); DG4P was used 7 days beyond MSL. At a clinical research center (CRC), subjects were randomized to receive the same breakfast with standard insulin bolus (standard) or a delayed and increased (delayed & increased) bolus to induce large glucose swings during weeks 1 and 2; venous glucose was checked every 5–15 min for 6 h. Subjects performed ≥4 reference fingersticks/day at home. Accuracy was assessed by differences in mean absolute relative difference (%MARD) in glucose levels compared with fingerstick test (home use) and YSI reference (CRC). During home-stay the Libre MARD was 13.7 ± 3.6% and the DG4P MARD 12.9 ± 2.5% (difference not significant [NS]). With both systems MARD increased during hypoglycaemia and decreased during hyperglycaemia, without significant difference between sensors. In the euglycaemic range MARD was smaller with DG4P [12.0 ± 2.4% vs 14.0 ± 3.6%, p = 0.026]. MARD increased in both sensors following delayed & increased vs. standard bolus (Libre: 14.9 ± 5.5% vs. 10.9 ± 4.1%, p = 0.008; DG4P: 18.1 ± 8.1% vs. 13.1 ± 4.6%, p = 0.026); between-sensor differences were not significant (p = 0.062). Libre was more accurate during moderate and rapid glucose changes. DG4P and Libre performed similarly up to 7 days beyond DG4P MSL. Both sensors performed less well during hypoglycaemia but Libre was more accurate during glucose swings. The study was registered in ClinicalTrials.gov (NCT02734745) April 12, 2016. •The accuracy of the Libre versus DG4P CGM sensors in type 1 diabetes patients was compared.•The DG4P manufacturer-specified lifetime (MSL) is 7 days; Libre MSL is 14 days.•DG4P performed as well as Libre up to 7 days beyond the specified MSL.•Libre was more accurate than DG4P during significant glycaemic excursions.