FIG. 1.
(A) Basic enzyme reactions. (B) Reaction on test strips (modified from multiple sources1–4,7,6). In current self-monitoring of blood glucose systems, the enzyme (glucose oxidase [GOD] or glucose dehydrogenase [GDH]) and its coenzyme catalyze the oxidation of glucose. A mediator is used as electron acceptor that transfers electrons from the enzyme–coenzyme complex to the electrode (reaction 1). Because oxygen is the physiological electron acceptor for the GOD enzyme, it is possible that O2 competes with the mediator (reaction 2). In GOD-based self-monitoring of blood glucose systems, increased or decreased O2 concentrations may result in underestimated (overestimated) blood glucose concentrations. ox, oxidized; red, reduced.