Graphite electrodes are modified with a redox polymer, [Os(4,4-dimethoxy-2,2-bipyridine)(2)(polyvinylimidazole)(10)Cl](+) (E degrees=-0.02V vs Ag/AgCl (3M KCl), crosslinked with a flavin adenine dinucleotide glucose dehydrogenase and multi-walled carbon nanotubes for electrocatalytic oxidation of glucose. The enzyme electrodes provide 52% higher current density, 1.22 +/- 0.10mAcm(-2) in 50mM phosphate-buffered saline at 37 degrees C containing 5mM glucose, when component amounts are optimised using a design of experiments approach compared to one-factor-at-a-time. Current densities of 0.84 +/- 0.15mAcm(-2) were achieved in the presence of oxygen for these enzyme electrodes. Further analysis of the model allowed for altering of the electrode components while maintaining similar current densities, 0.78 +/- 0.11mAcm(-2) with 34% less enzyme. Application of the cost-effective anodes in membrane-less enzymatic fuel cells is demonstrated by connection to cathodes prepared by co-immobilisation of [Os(2,2-bipyridine)(2)(polyvinylimidazole)(10)Cl+] redox polymer, Myrothecium verrucaria bilirubin oxidase and multi-walled carbon nanotubes on graphite electrodes. Power densities of up to 285Wcm(-2), 146Wcm(-2) and 60Wcm(-2) are achieved in pseudo-physiological buffer, artificial plasma and human plasma respectively, showing promise for invivo or ex vivo power generation under these conditions.