A microneedle-based self-powered biofuel-cell glucose sensor is described. The biofuel cell sensor makes use of the integration of modified carbon pastes into hollow microneedle devices. The system displays defined dependence of the power density vs glucose concentration in artificial interstitialfluid. An excellent selectivity against common electroactive interferences and long-term stability are obtained. The attractive performance of the device indicates considerable promise for subdermal glucose monitoring.