Abstract: A method for measuring glucose concentration in a biological material is disclosed, as well as a computer readable medium and a sensor system for performing the method. The method comprises irradiating the biological material with optical radiation having a first wavelength between 400 nanometers and 25 micrometers; detecting a first signal from the biological material at the first wavelength; irradiating the biological material with radio-frequency, RF, radiation having a second wavelength between 1 millimeter and 30 centimeters; detecting a second signal from the biological material at the second wavelength; and determining a concentration of glucose in the biological material based on the first signal and the second signal. The sensor system comprises an optical radiation source, an optical radiation detector, an RF radiation source, and RF radiation detector, and a processing device.