An apparatus for determination of a glucose concentration in a biological matrix includes an irradiation device for irradiating light as primary light into a biological matrix, and a detection device for measuring intensity of light emerging as secondary light through the boundary surface of the biological matrix. The detection device detects light from the irradiation device after the light has propagated along a light path in the biological matrix. A data processing device processes measurement signals from the detection device. The irradiation device provides spatially limited illumination of an irradiation site, and the detection device is configured for spatially limited measurements of the secondary light emerging at the detection site. The detection site is located relative to the irradiation site such that the secondary light is multiply scattered at scattering centers in the biological matrix. The irradiation and detection devices are configured to provide at least two different light paths within the biological matrix during detection measurements, and to perform at least two detection measurements wherein the light paths are different. The detection device generates separate measurement signals for each of the at least two detection measurements. The data processing device converts the separate measurement signals into a signal which corresponds to a glucose concentration in the biological matrix.