Contained herein is a system and method for using non-contact diffuse optical skin reflectance method to obtain remote sensing of in-vivo glucose levels in biological tissue or fluids. One embodiment uses an optical, non-contact method capable of measuring glucose levels at a stand-off distance of 0.5 to 2 meters. In this method, the tissue is illuminated with a collimated beam of near-infrared (optical) band of light having a specific band of wavelengths. The diffuse reflectance measured from the tissue/fluid is collected while varying the optical circuit. Using the collected data, an algorithm to unravel the mixed effects of tissue/fluid scattering and absorption is applied to determine the absorption level of the light, which is then associated with a quantitative glucose level.