Existing electrochemical glucose sensors are either single use sensors produced in mass fabrication technologies or rather big sensors for multiple use with membranes to be changed frequently. Single use means no sensor maintenance but has the disadvantage that quality control measurements cannot be done with the same sensor used for the sample. Generally also the cost per test is relatively high. Multiple use sensors give the possibility of closer quality control and they are generally cheaper than the single use sensors for higher sample frequency but have the disadvantage of frequent need of remembraning. This often means special training and is a health risk due to sensor contamination by biological fluids. We combined the advantages of both principles meaning that we developed a new glucose sensor for multiple use in an essentially planar technology - thus being able to be produced very cheap. The underlying basic working principle is using glucose oxidase and detecting hydrogen peroxide. Due to the carbon base of the sensor it has a large surface area and therefore a very high sensitivity (microamps range at biological glucose concentrations) although the sensor itself is very small needing only about 10 microL of sample. The sensor shows a linear range of up to 40 mmol/L, a life time in use of far more than 1000 human serum samples and correlation coefficients between plasma and whole blood of r = 0.99. Interferences are well within clinical acceptability. Thus we conclude that this sensor works well in undiluted human body fluids and due to the very cheap production processes the whole sensor can be exchanged when it is old thus eliminating any need for remembraning or special maintenance.