Abstract: The paper followed the possible relationship between variability of contrast sensitivity tests and glycemic level in non-proliferative diabetic retinopathy using Spectral Domain OCT (SD-OCT), during daytime, related to changes of normal retinal layers. For this task, we investigated eyes with non-proliferative diabetic retinopathy (mild, medium and severe forms) by assessing the contrast sensitivity through Pelli Robson Test and micro-perimeter and retinal thickness using SD OCT. The images were analyzed using two software: ImageJ and Maviiss 1.5 (Mtf-bAsed Visible and Infrared Imaging System Simulation). The diabetic group was matched by similar control group (for age and sex) of healthy eyes. Our results showed a correlation between the retinal thickness during daytime, contrast sensitivity loss and glycemic variations that can be used as further investigation tool.