Monitoring of metabolic compounds, such as glucose and lactate, is extensively reported in literature, especially for clinical purposes. Instead, the application of such technologies for monitoring metabolites in cell cultures has not been explored. From one side, such devices can provide information to the current state-of-the-art of cell lines, particularly those which are not fully known, as stem and embryonic cells. On the other hand, those systems can pave the way to fully automation for growing cell cultures, when coupled with robots for feeding. Among different presented strategies to develop biosensors,carbon nanotubes exhibit great properties, particularly suitable for biosensing. In this work nanostructured electrodes by using multi-walled carbon nanotubes are presented for the detection of glucose and lactate. Firstly, some results from simulations are illustrated in order to foresee the behavior of carbon nanotubes depending on their orientation, when they are dispersed onto the electrode surface. Then, such developed biosensors are characterized in terms of sensitivity and detection limit, and are compared to previously published results. Finally, monitoring of a cell culture is performed and the behavior of metabolites is analyzed as biosensors validation.