An oxidative peak in a cathodic scan is observed in the cyclic voltammetry of glucose at gold electrodes, its peak current density being proportional to glucose concentration in a wide potential range. The application of this phenomenon in blood glucose sensing has been hindered by the presence of inhibitors: the most problematic are chlorides due to their high concentration and difficult separation from glucose. The present invention provides a solution to this problem involving a three electrode, four step pulsed electrochemical detection technique.