Error detection and measurement in glucose monitors

In a quality review of glucose monitors, we measured the inaccuracy and imp recision of 26 systems. In each case, measurements on at least 50 capillary specimens from diabetic patients were compared with results from capillary blood that had been deproteinized and assayed with hexokinase. We also tes ted the monitors with commercial control solutions. In patients' specimens having a mean blood glucose concentration of about 9 mmol/l, the bias of th e 26 monitors ranged from -5.1 to +20.1% (median = +7.5%). Imprecision of t he monitors with blood specimens gave coefficients of variation (CV) rangin g from 4.5% to 22.8% (median = 8.7%) at the mean glucose concentration. A c ontrol solution for the monitors gave a glucose concentration of 7.6-13.6 m mol /1 (median = 9.2 mmol/l) with CV that varied from 1.7 to 19.8% (median = 4.7%). While the means and CV's of the control were significantly correla ted with bias and imprecision of the blood specimens, much of the variance remained unexplained (for bias, r(2) = 0.17; for imprecision, r(2) = 0.43). We conclude that a common basis for calibration could remove a significant component of variation and that control solutions may give a false impress ion of analytical performance. (C) 2001 Elsevier Science B.V. All rights re served.