There are a number of factors influencing the outcome of a BG monitoring system in this kind of investigation. First, lotto-
lot differences of a given BG monitoring system are not detected by assessing only one lot. Thus it could be useful to
analyze several lots in order to evaluate a BG monitoring system. Second, the overall errors observed in a method comparison always include the error of the reference method, i.e.,there is a significant contribution of the reference method to the inaccuracies reported here. The contribution of different reference methods with respect to inaccuracy of the overall result of the BG monitoring systems might be different. For example, Twomey18 found the YSI 2300 STAT, using the glucose oxidase method, to be negatively biased for plasma glucose when compared with the Olympus (Tokyo, Japan)
AU640 hexokinase method. These differences between reference
methods would introduce additional bias that is not
due to the BG monitoring systems tested. Third, the conversion
factor from whole blood BG values to plasma equivalent
BG values is specific for the manufacturer. Not all manufacturers
stick to the recommendations of the International
Federation of Clinical Chemistry19 on reporting of BG results.
The results may also vary depending on whether whole blood