A more elaborate configuration of the apparatus with a salt bridge, made of 2% agar in incubation buffer, allowed conductive contact with the nitrocellulose near the spot of glucose oxidase and the buffer in the upper reservoir and increased the linear range. This salt bridge was easily damaged by drying, however, when the system was temporarily unused. Moreover, for diabetes, most informative urinary glucose concentrations lie in the linear range of the method we present here. Accurate quantitative information for higher concen- trations is usually not needed in practice, and these concentrations are labeled simply as “very high” (in the event that it is useful to measure higher concentrations, an extra dilution step could be added to enable better quantitation). We note that, for monitoring diabetes, low concentrations in urine (in the range of 0−2 mM) are sometimes not informative,