Abstract: A device is described for measuring a parameter of living tissue, in particular a glucose level, which parameter affects a response of said tissue to an electric field. The device comprises a substrate (2), which carries a ground electrode (10) as well as a plurality of signal electrodes (12a, 12b, 13a-13c, 14). The gaps (15) between the ground electrode and the signal electrodes are filled with a solid filler material (16) in order to provide an even surface. Optical reflection detectors (23a, 23b, 23c) can also be located in these gaps in order to avoid field distortions and obtain a compact design. The backside of substrate (2) carries electronic high-frequency components for improving signal quality.