Uniform latex particles and agarose gels are utilized to create porous membranes in which polypyrrole is electrochemically synthesized. Within the pores of these modified membranes glucose oxidase can be adsorbed irreversibly while its catalytic activity is retained. A glucose sensor which has a considerable lifetime under continuous use is constructed from the enzyme membrane. With this sensor glucose can be measured amperometrically in the concentration range 1-60 mM. The sensor response is independent of oxygen concentration.