Accuracy of the Enlite 6-Day Glucose Sensor with Guardian and Veo Calibration Algorithms

Objective: This study investigates the accuracy of a newly developed, next-generation subcutaneous glucose sensor, evaluated for 6-day use. Research Design and Methods: Seventy-nine subjects (53 men, 26 women) with type 1 diabetes and 18 subjects (14 men, four women) with type 2 diabetes completed a three-center, prospective, sensor accuracy study. The mean age for the group was 42.2 +/- 15.0 years (mean +/- SD), ranging from 18 to 71 years, with a mean glycosylated hemoglobin level of 7.6 +/- 1.5%, ranging from 5.5% to 14%. Subjects wore Enlite(TM) sensors (Medtronic Diabetes, Northridge, CA) in the abdominal and buttocks region for two separate 7-day periods and calibrated with a home-use blood glucose meter. Subjects participated in an in-clinic testing day where frequent sampled plasma glucose samples were acquired every 15 min for 10 h. Sensor data was retrospectively processed with Guardian(R) REAL-Time (Medtronic) and Paradigm(R) Veo(TM) (Medtronic) calibration routines, and accuracy metrics were calculated for each algorithm and sensor location. Physiological time lag for each measurement site was calculated. Results: Based on 6,404 plasma-sensor glucose paired points, the Enlite sensor with Veo calibration algorithm produced a mean absolute relative difference of 13.86% with 97.3% of points within the A+B zones of the Clarke error grid. Threshold-only alarms detected 90.1% of hypoglycemia and 90% of hyperglycemia. Mean time lag measured at the abdominal region was 7.94 +/- 6.48 min compared with 11.70 +/- 6.71 min (P < 0.0001) at the buttocks area. Conclusions: The Enlite sensor accurately measures glucose when compared with gold standard laboratory measurements over its 6-day use. Sensors placed in the buttocks region exhibited greater time lags than sensors placed in the abdomen.