Diagnostic sensor unit for non-invasive detection of at least one physiological parameter of body tissue close to the skin surface, - having an optical measurement unit that comprises two or more radiation sources for irradiating the body tissue to be examined, and at least one radiation sensor for detecting the radiation scattered and/or transmitted by the body tissue, - having an ECG-unit for detecting an ECG-signal by way of two or more ECG-electrodes, - having a temperature- or heat measurement unit connected with a temperature-or heat sensor, - having a bioelectrical impedance measurement unit, - having a sensor housing, whereby - the two or more radiation sources, the at least one radiation sensor, the ECG unit, the temperature or heat measurement unit and the bioelectrical impedance measurement unit are disposed in a common sensor housing, - whereby at least one ECG-electrode of the ECG unit is disposed on the housing surface of the sensor housing, in such a way, that the ECG-electrode touches the skin surface in the region of the body tissue covered by the optical measurement unit, and - whereby at least one feed or measurement electrode of the impedance measurement unit is disposed on the housing surface of the sensor housing, characterized by that the at least one ECG-electrode is configured as a planar foil or sheet of electrically conductive material, - the ECG-electrode has at least one recess for passage of the radiation emitted by the two or more radiation sources into the body tissue to be examined, a recess (420, 430) for passage of the scattered light in the body tissue and one other recess for the temperature and heat sensor, - the two or more radiation sources are connected with a light-conducting element that guides the radiation of the at least two radiation sources (4, 4') to the surface of the sensor housing, and - the two or more radiation sources, the at least one radiation sensor and the temperature or heat sensor are disposed on a common board within the sensor housing. - having an optical measurement unit that comprises two or more radiation sources for irradiating the body tissue to be examined, and at least one radiation sensor for detecting the radiation scattered and/or transmitted by the body tissue, - having an ECG-unit for detecting an ECG-signal by way of two or more ECG-electrodes, - having a temperature- or heat measurement unit connected with a temperature-or heat sensor, - having a bioelectrical impedance measurement unit, - having a sensor housing, whereby - the two or more radiation sources, the at least one radiation sensor, the ECG unit, the temperature or heat measurement unit and the bioelectrical impedance measurement unit are disposed in a common sensor housing, - whereby at least one ECG-electrode of the ECG unit is disposed on the housing surface of the sensor housing, in such a way, that the ECG-electrode touches the skin surface in the region of the body tissue covered by the optical measurement unit, and - whereby at least one feed or measurement electrode of the impedance measurement unit is disposed on the housing surface of the sensor housing, characterized by that the at least one ECG-electrode is configured as a planar foil or sheet of electrically conductive material, - the ECG-electrode has at least one recess for passage of the radiation emitted by the two or more radiation sources into the body tissue to be examined, a recess (420, 430) for passage of the scattered light in the body tissue and one other recess for the temperature and heat sensor, - the two or more radiation sources are connected with a light-conducting element that guides the radiation of the at least two radiation sources (4, 4') to the surface of the sensor housing, and - the two or more radiation sources, the at least one radiation sensor and the temperature or heat sensor are disposed on a common board within the sensor housing.