Biosensors for endogenous compounds, such as glucose and lactate, are applied to monitor cell cultures. Cells can be cultivated for several purposes, such as understanding and modeling some biological mechanisms, the development of new drugs and therapies, and in the field of regenerative medicine. We have realized a self-contained monitoring system with remote readout. Metabolite detection is based on oxidases immobilized onto carbon nanotubes. We calibrate the system for glucose and lactate detection in phosphate buffer solution. A hw/sw architecture records the signal generated by the biosensor and transmits it to a remote station by means of a Bluetooth module. We have validated two biosensors for metabolic monitoring in culture medium and we detect lactate production in neuroblastoma cells after 72 h of cultivation. The integrated system proposed in the present work opens new opportunities towards the development of novel tools for cell analysis.