In this study, we compared the blue-on-yellow perimetric parameters with conventional automated static threshold perimetric parameters in the detection of psychophysical abnormality in patients with type 1 diabetes mellitus (DM) without diabetic retinopathy. Forty-three patients with type 1 DM without diabetic retinopathy were included this study. Thirty subjects served as age-matched control group. Blue-on yellow perimetry was performed and the results compared to white-on-white perimetry. The values of mean deviation by blue-on-yellow perimetry in the diabetic group were significantly higher than in the control group (P=0.0001). The indices of short fluctuation, pattern standard deviation, corrected pattern standard deviation and foveal sensitivity which all relate to localized depression in sensitivity were similar in both groups. The achromatic perimetric parameters were not different between the groups. We conclude that the short-wavelength-sensitive cones are vulnerable to damage from hyperglycemia and this influence can be detected early by blue-on-yellow perimetry in diabetic patients without retinopathy.