Measurement of blood glucose

Abstract

Inevitable numerous publications are available on method comparisons. These have compared enzymic with colorimetric procedures, kinetic with equilibrium techniques, or the effects of instrumental adaptations to one particular method. The reader is referred to these articles for the relative performance of glucose methods. Some generalisations are apparent such as the increased specificity of enzymic methods compared to chemical methods. However, factors other than accuracy may have to be considered by those confronted with the problem of choosing the 'best' method for their laboratory. The choice of method may be dependent on the clinical requirements, the type and number of specimens or the facilities available. Of the solution chemistries, the glucose dehydrogenase methods combine the considerable advantages of simplicity, specificity and speed. The widespread acceptance of this relatively new method by routine laboratories for the determination of large number of samples is at present limited only by the cost of the reagents. However, glucose dehydrogenase has a larger turnover number than hexokinase or glucose oxidase and consequently may prove to be of even greater value in solid-state glucose sensors in the future. For stat chemistry or the smaller laboratory, glucose oxidase linked to an electrode bypasses most of the interference associated with the lack of specificity of this method and gives rapid results. Dry chemistry reagent strips may also be of value in this situation since in the laboratory they have been shown to give comparable performance. Little information is available on their specificity and they may be subject to the same non-specific interferences as the solution glucose oxidase methods; in this respect one might expect interference to be more severe as the sample itself is the solvent and the relative concentration of interferents is greater therefore. Colorimetric procedures may retain their place only in situations such as primary health care centres where reagent stability and cost are major factors; even here the dry chemistry reagent strips may offer greater advantages.