Tissue intrinsic fluorescence spectrum refers to the fluorescence that is not impaired by tissue absorption and scattering which has the ability to reflect tissue biochemical properties. In order to reduce the influence of tissue absorption and scattering properties on tissue fluorescence spectrum, and then recover tissue intrinsic fluorescence spectrum, a tissue spectrum detection system based on fiber-optic probe was developed for the measurement of tissue fluorescence spectrum and diffusion reflectance spectrum at the same place. On the other hand, diffusion theory was introduced to extract the tissue physiological parameters from the measurement tissue diffusion reflectance spectrum, which included blood volume fraction, oxyhemoglobin saturation, melanin content, reduce scattering coefficient at 500 nm and the ratio of rayleigh scattering and the total scattering. Then tissue optical parameters in visible wavelengths were calculated. According to the tissue optical parameters and measured tissue diffusion spectrum, the intrinsic fluorescence spectrum was recovered from the measured fluorescence. Based on this, clinical trials were conducted to measure human skin fluorescence spectrum and diffusion reflectance spectrum, and then to recover skin intrinsic fluorescence spectrum. Finally, the accumulation of Advanced Glycation End products (AGE) in human skin was evaluated and the probability of diabetes mellitus was predicted. The result shows that the sensitivity and specificity were 69% and 0.75% respectively, when the measured fluorescent was used to screening diabetes mellitus. At the same specificity, the sensitivity was 90% when the recovered intrinsic fluorescence was employed to screening diabetes mellitus.