Color perception is often already altered even if the ocular, anatomic and functional exams maintain their results within the normal limits. This fact is more important in diabetes, where chromatic abnormalities exist at half of the subjects, even if they do not reveal any signs of diabetic retinopathy. The authors present some of the methods in clinical exam of color perception, the characters of dyschromatopsia and glycemic self control using the method of coloured bandelets, types of dyschromatopsia which may appear during the evolution of the diabetes, and also the predictive effect of dyschromatopsia for the appearance of diabetic retinopathy.