Near-infrared photons propagate in the mixed solution of intralipid and glucose and form diffuse reflection. In steady state, the scattered photons at the detection spot include ballistic photons, quasi-ballistic photons, and scattered photons, and part of ballistic photons and scattered photons decrease the detection accuracy of glucose concentration. By Monte Carlo time-domain simulations of 10% and 3%intralipid-glucose solution respectively, different path-length components of diffuse reflection at different detection spots were statistically analyzed. It is shown that both the peak time of the detection time expansion curve and diffuse reflection photons in the average flying time can improve the detection accuracy of the point of floating reference, where the diffuse reflection is the most insensitive to the glucose concentration. Moreover, these photons increase, at the maximum intensity of diffuse reflection, the coefficients of linear dependency between the intensity of diffuse reflection and glucose concentration. Thus, extraction of the diffuse reflection corresponding to this path-length improves the detection sensitivity of glucose concentration.