The system (1) has an implantable sensor (3) producing measuring signals correlated with analytical concentration. A base station (2) has an electronic evaluation unit (47) i.e. microprocessor, evaluating the measuring signals and a transmitter (31) for wireless transmission of evaluation results. The evaluation unit statistically evaluates the measuring signals as raw data in a mode and produces measurement data from the raw data. The measurement data is transmitted to a display device (4). The evaluation unit determines an analytical concentration value by evaluating the measurement data.