A Laboratory Trial of Two New Blood-Glucose Reflectance Meters Featuring Automatic External Calibration

Abstract

Two new battery-operated digital reflectance meters for blood glucose measurement have been tested for precision and accuracy in a laboratory trial. Reflocheck® (Boehringer Company Ltd) is calibrated from a bar code printed on each test strip, Reflolux® (Boehringer Company Ltd) from a bar code on acetate film provided with each bottle of BM-Test-Glycemie 20–800R strips, which can also be read visually. Three aqueous standards (3·3, 8·3 and 11·7 mmol/1) were assayed 10 times on each of 10 days. Overall coefficients of variation for Reflocheck were 2·8, 1·7 and 2·0% and for Reflolux 3·1, 1·5 and 2·8% respectively. One hundred and four blood samples measured on the machines gave very high correlations with a manual hexokinase assay: for Reflocheck, y = 1·1 x — 0·7, r = 0·99 and for Reflolux, y = 1·07 x + 0·1, r = 0·99. In the range 2·2–10 mmol, errors of 1 mmol or more occurred on seven occasions with Reflocheck and eight with Reflolux ( n = 80) but none of these errors was of therapeutic significance. The performance of both machines was as good or better than previously published data for similar instruments. The ease of calibration and accuracy of both machines are advantageous as is the use of BM-Test-Glycemie 20–800R by Reflolux which enables a check to be made on visual readings.