A Critical Appraisal of the Continuous Glucose–Error Grid Analysis

clinically apparent that when blood glucose is Ͻ3.9 mmol/l point accuracy should be given more emphasis than rate accuracy.A strength of CG-EGA is its ability to vary the input of either rate or point accuracy to overall clinical accuracy depending on blood glucose range.Third, the results of CG-EGA vary with time intervals.This is also an intuitive strength of CG-EGA, which is designed to account for increased noise associated with frequent sampling.We advocated (2) adopting a uniform sampling protocol with reference and/or sensor pairs taken every 10 -15 min to standardize comparisons of rate accuracy, which is a sampling scheme based on physiological considerations of possible glucose change rates.Fourth, Wentholt et al. (1) questioned the appropriateness of the formulae to shift point EGA based on interstitial time lag.However, the authors reported an average time lag of ϳ7 min in one of their sensors, which is identical to that assumed for CG-EGA, thus confirming that ϳ7 min is a reasonable average for blood-tointerstitial diffusion delays.CG-EGA software allows setting this parameter to any value Ͻ7 min.We are pleased that both the discussion regarding CG-EGA and the analysis of time series data have begun, and we look forward to continuing this important dialogue.However, we also recommend careful consideration of basic statistical assumptions when analyzing sensorgenerated glucose data; their inherent temporal structure should be taken into account.