Improving the quality of self-monitoring blood glucose measurement: a study in reducing calibration errors.

BACKGROUND: Two independent studies reported that 16% of people who self-monitor blood glucose used incorrectly coded meters. The degree of analytical error, however, was not characterized. Our study objectives were to demonstrate that miscoding can cause analytical errors and to characterize the potential amount of bias that can occur. The impact of calibration error with three selfblood glucose monitoring systems (BGMSs), one of which has an autocoding feature, is reported. METHODS: Fresh capillary fingerstick blood from 50 subjects, 18 men and 32 women ranging in age from 23 to 82 years, was used to measure glucose with three BGMSs. Two BGMSs required manual coding and were purposely miscoded using numbers different from the one recommended for the reagent lot used. Two properly coded meters of each BGMS were included to assess within-system variability. Different reagent lots were used to challenge a third system that had autocoding capability and could not be miscoded. RESULTS: Some within-system comparisons showed deviations of greater than +/-30% when results obtained with miscoded meters were compared with data obtained with ones programmed using the correct code number. Similar erroneous results were found when the miscoded meter results were compared with those obtained with a glucose analyzer. For some miscoded meter and test strip combinations, error grid analysis showed that 90% of results fell into zones indicating altered clinical action. Such inaccuracies were not found with the BGMS having the autocoding feature. CONCLUSIONS: When certain meter code number settings of two BGMSs were used in conjunction with test strips having code numbers that did not match, statistically and clinically inaccurate results were obtained. Coding errors resulted in analytical errors of greater than +/-30% (-31.6 to +60.9%). These results confirm the value of a BGMS with an automatic coding feature.

Evaluation of a new blood glucose monitoring system with auto-calibration for home and hospital bedside use.

A new self-calibrating blood glucose monitoring system (BGMS) was evaluated in a series of clinical studies with both ambulatory subjects and with hospitalized patients. The new BGMS requires a 0.6microL sample volume, provides results in 15s, and uses a glucose dehydrogenase chemistry that is oxygen independent. In the first study, Ascensia Contour meters calibrated to whole blood were tested by health care professionals (HCP) and lay users at two clinical sites. Both HCPs and lay users obtained results that fulfilled the ISO 15197:2003 criteria that 95% of self-monitoring blood glucose (SMBG) measurements should fall within +/-20% (for blood glucose (BG) concentrations> or =4.2mmol/L or +/-0.83mmol/L for BG concentrations<4.2mmol/L) of the laboratory value. Lay users and HCPs obtained 97.2 and 96.7% of glucose results within ISO criteria, respectively. In a second study, HCPs assayed blood samples from patients at the hospital bedside using meters calibrated to give whole blood glucose and meters calibrated to give plasma glucose results. Overall, 94.7% of the measurements met the ISO 15197:2003 criteria. Most lay subjects rated the BGMS as either excellent or very good in a questionnaire, and were able to use it properly without training. These findings indicate that this new BGMS is a convenient and accurate instrument system suitable for both hospital bedside use by HCPs and for SMBG by people who routinely monitor their blood glucose.