Evaluating the Accuracy, Reliability, and Clinical Applicability of Continuous Glucose Monitoring (CGM): Is CGM Ready for Real Time?

Abstract Background: This study was designed to assess the accuracy, reliability, and contribution to clinical decision-making of two commercially available continuous glucose monitoring (CGM) devices using a novel analytical approach. Study design: Eleven individuals with type 1 diabetes and five with type 2 diabetes wore a Guardian® RT (GRT) (Medtronic Minimed, Northridge, CA) or DexCom™ STS™ Continuous Monitoring System (DEX) (San Diego, CA) device for 200 h followed by an 8-h laboratory study. A subset of these subjects wore both devices simultaneously. Results: Subjects produced 1,902 ± 269 readings during the ambulatory phase. During the laboratory study we found: lag time of 21 ± 5 min for GRT and 7 ± 7 min for DEX (P < 0.005); mean absolute relative difference of 19.9% and 16.7%, respectively, for GRT and DEX; and glucose exposure (the ratio of study device/laboratory reference device [YSI Instruments, Inc., Yellow Springs, OH] area under the curve) of 95 ± 6% for GRT and 101 ± 13% for DEX. Reliab...