A Pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase based platinum electrode was developed to detect glucose. Chromium hexacyanoferrate was modified onto this electrode to serve as an electron transfer mediator between PQQ and the platinum electrode. This biosensor showed the optimal response of glucose measurements at pH 7 and an operation potential of +0.4 V (vs. Ag/AgCl). More importantly the lifespan of the biosensor has been last for 47 days without significant enzyme activity degradation.