The introduction of tight glycemic control protocols in hospitals has increased the need for more accurate bedside glucose meters. In 1987, the American Diabetes Association (ADA) recommended that glucose meters should have a total error (analytic plus user) of < 10% at glucose concentrations between 30 to 400 mg/dL. More recently, ADA urged manufacturers to further decrease total error to 5%. Currently available meters do not meet these performance goals. Recent proficiency testing results from the College of American Pathologists demonstrate that glucose meters have much more instrument to instrument variability than chemistry analyzers in central laboratories. For example, the interlaboratory precision at a glucose value of 400 mg/dL ranged from 4.1% to 13.7% for glucose meters compared to 1.6% to 2.8% for chemistry analyzers.
The laboratory often receives questions concerning the disparity between a glucose result obtained with a glucose meter and a subsequent result performed on a chemistry analyzer in the laboratory. In most instances, the glucose meter result has been incorrect. The most common causes of erroneous results obtained with glucose meters include:
- Under or overfilling of the glucose strip
- Contamination or dilution of the sample, especially if drawn from a line
- Clotting of the sample due to delayed testing
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