An implantable sensor is provide which can be used for determining a concentration of at least one analyte in a medium, in particular a body tissue and/or a body fluid. The implantable sensor has a layered construction with at least one insulating carrier substrate and at least two electrodes which are arranged in at least two different layer planes of the implantable sensor and are electrically isolated from one another by the at least one insulating carrier substrate. The electrodes have electrode areas which face the medium when the sensor has been implanted, and are in contact with the medium over a large area and substantially uniformly, directly or via a generally analyte-permeable membrane layer.
