Previous techniques for sensing and measuring glucose are briefly reviewed and compared. The genesis of the glucose coated wire electrode lies in liquid membrane technology, and the basic principle of the electrode is described. The electrode utilizes a quaternary ammonium salt with a sparingly soluble metallic salt of glucose, in a matrix such as poly(vinyl chloride). Fabrication procedures are detailed. Typical sensor responses are illustrated with experimental data. The sensor generally shows a voltage that decreases linearly with increasing glucose concentration over approximately 40 mg/dl to 200 mg/dl. The time response of the sensor is of the order of seconds, and the lifetime observed to date is of the order of several months. Initial studies of mechanism are discussed, using liquid NMR. Preliminary interference effect studies to date are summarized, in which common compounds such as ascorbic acid, uric acid, L-cystine, glycine, and bilirubin were used. Singly these compounds show no significant interference effects.