A detecting device for detecting a blood sugar concentration in a blood vessel, comprising: a signal generator designed to generate a first electrical excitation signal having a frequency between 1 MHz to 100 GHz and a second electrical excitation signal, wherein the signal generator is designed to generate a calibration measurement signal, the calibration measurement signal comprising a superimposition of the first excitation signal and the second excitation signal, - wherein the first excitation signal has a higher frequency than the second excitation signal and/or the second excitation signal is a direct signal and/or - wherein the second excitation signal has a higher power than the first excitation signal; a transceiver arrangement designed to emit the calibration measurement signal in the direction of the blood vessel and to receive a first system response signal in response to the emission of the calibration measurement signal; wherein the transceiver arrangement is designed to emit a third excitation signal in the direction of the blood vessel and to receive a second system response signal in response to the emission of the third excitation signal; and a processor designed to link the first system response signal and the second system response signal in order to obtain a measurement signal for determining the blood sugar concentration, characterized in that the signal generator is designed to generate a clear signal, in particular a stationary or subsiding alternating signal, for clearing a polarization of dipoles in the blood vessel caused by the calibration measurement signal, the transceiver arrangement being designed to emit the clear signal in the direction of the blood vessel. a signal generator designed to generate a first electrical excitation signal having a frequency between 1 MHz to 100 GHz and a second electrical excitation signal, wherein the signal generator is designed to generate a calibration measurement signal, the calibration measurement signal comprising a superimposition of the first excitation signal and the second excitation signal, - wherein the first excitation signal has a higher frequency than the second excitation signal and/or the second excitation signal is a direct signal and/or - wherein the second excitation signal has a higher power than the first excitation signal; - wherein the first excitation signal has a higher frequency than the second excitation signal and/or the second excitation signal is a direct signal and/or - wherein the second excitation signal has a higher power than the first excitation signal; a transceiver arrangement designed to emit the calibration measurement signal in the direction of the blood vessel and to receive a first system response signal in response to the emission of the calibration measurement signal; wherein the transceiver arrangement is designed to emit a third excitation signal in the direction of the blood vessel and to receive a second system response signal in response to the emission of the third excitation signal; and a processor designed to link the first system response signal and the second system response signal in order to obtain a measurement signal for determining the blood sugar concentration, characterized in that the signal generator is designed to generate a clear signal, in particular a stationary or subsiding alternating signal, for clearing a polarization of dipoles in the blood vessel caused by the calibration measurement signal, the transceiver arrangement being designed to emit the clear signal in the direction of the blood vessel.