Evaluation of blood glucose measurement techniques: locating sources of error

Researchers evaluating the accuracy of rapid blood glucose monitoring (RBGM) techniques have often concluded that RBGM was sufficiently accurate for clinical use. However, investigators of patients' use of RBGM have more often reported unacceptable levels of accuracy and have shown individual differences between patients in the level of accuracy attained. Responsibility for excessive errors has commonly been attributed to patients' inadequacy in using RBGM. The logic of such attributions is questioned. Data are presented which indicates that errors attributed to patient inaccuracy may actually be due to (a) inaccuracy of reference blood glucose determinations used to evaluate patients' accuracy and (b) variable accuracy of RBGM techniques dependent on the range of blood glucose levels: some patients may appear to be less accurate than others simply because their blood glucose levels fall into a range less accurately measured by the RBGM technique. Furthermore, data presented reveal batch to batch variation in accuracy of the particular reagent strips used. Such variation between batches may help to account for inconsistencies between RBGM evaluation studies in which apparently identical reagent strips were used.