Evaluation of subcutaneous glucose monitoring systems under routine environmental conditions in patients with type 1 diabetes

Abstract: Continuous and flash glucose monitoring (GM) systems have been established in diabetes care. We compared sensor performance of three commercially available GM systems. 12 patients with type 1 diabetes were included in a single-centre, open-label study where sensor performance of Abbott FreeStyle libre (Abbott), Dexcom G4 Platinum (Dexcom) and Medtronic MiniMed 640G (Medtronic) over 12 hours was compared during mimicked real- life conditions (meals, exercise, hypo- and hyperglycaemia). Sensor performance was determined by fulfilment of ISO 15197:2013 criteria, calculating mean absolute relative difference (MARD) as well as illustrated by Parkes Error grid and Bland-Altman plot. Sensor performance during changes of metabolic parameters (lactate, betahydroxybutyrate, glucagon, non-esterified-fatty-acids) was determined by Spearman`s rank correlation coefficient testing. The systems fulfilled ISO 15197:2013 criteria by 73.2% (Abbott), 56.1% (Dexcom) and 52.0% (Medtronic). MARD in the entire glycaemic range was 13.2% ± 10.9% (Abbott), 16.8% ± 12.3% (Dexcom) and 21.4% ± 17.6% (Medtronic), respectively. All sensors performed less accurately during hypoglycaemia and best during hyperglycaemia. We could not observe an influence of metabolic parameters on sensor performance.