A method and system for detecting glucose in a biological sample is disclosed. This includes illuminating a biological sample with a light source, collecting transmitted, transflected or reflected light from the sample with a detector, generating spectral data of one or more components in the sample other than glucose in a spectral data analysis device, and analyzing the spectral data of the one or more components, sufficient to provide a glucose measurement from the spectral data of the one or more components other than glucose with the spectral data analysis device.