The monitoring of metabolic compounds such as glucose is largely reported in literature. The applications of this type of analysis are mainly related to clinical purposes, e.g. in diabetes pathology, where a lot of studies are presented in literature. Recently, some authors presented studies about glucose and lactate detection in cell culture monitoring , . A clear identification of medium compounds could be interesting for biologists and biotechnologists, since they may be identified as markers of different cell states. It can also pave the way to automated systems, as a feedback of the medium state. In the field of amperometric biosensors, a lot of techniques related to the structuration of the electrodes have been presented in the last twenty years. Especially for glucose biosensors, a lot of mediators have been employed to carry the electrons released from the redox reaction to the surface of the electrode , . Recently, some authors presented great results in terms of sensitivity and limit detection by using nanostructured electrodes. The employment of carbon nanotubes has shown promising results, due to their ability to promote the electron transfer from the active site of the enzyme onto the surface of the electrode, because of their electrocatalytic properties. Since we observed an improvement in terms of sensitivity and detection limit by using Multi-walled Carbon Nanotubes (MWCNT) for hydrogen peroxide (H2O2) detection, we decided to modify the nanostructured electrodes with glucose oxidase (GOD), since glucose is the most interesting compound in cell culture. We dropped 40 µl (1 mg ml-1) MWCNT onto Screen Printed Electrodes (SPE) purchased from Dropsens (Spain), and after, we deposited a certain quantity of GOD (3.5 U mm-2) and we stored the electrode overnight at +4°C. The result of the detection from chronoamperometry in stirring conditions with PBS as support electrolyte is shown in Figure 1.