The analytical detection of d-glucose by means of self-catalytic carbon paste electrodes is described. In the construction of these electrodes, carbon powder has been modified with the redox liquid n-butylferrocene, which simultaneously serves both to help bind the paste together whilst also acting as a mediator in the enzymatic oxidation of d-glucose by glucose oxidase. The sensor then functions by monitoring the electrochemical oxidation of the constituent n-butylferrocene itself. Through testing in model glucose solutions, the electrodes were found to yield a linear response over a d-glucose concentration range of 2-20 mM. They were also successfully employed in the determination of d-glucose levels in a spiked blood sample, giving a detection limit of 0.8 mM (based on the 3sigma criterion).