Background Diabetic retinopathy is the most important complication of DM affecting the eye, and is a leading cause of legal blindness among working age individuals 1. DR, is known to have its etiopathogenesis related to microvascular damage, increased vascular permeability and endothelial cell proliferation. Newer evidence suggests an alternate pathway of neurodegenerative damage occurs where the pathological changes may begin in the neural layers of the retina 2. OCT is, non invasive diagnostic technique that provides highly reliable and objective cross sectional images of the retina allowing accurate measurement of retinal layers including GCC 3. Aim To assess thickness of retinal GCC in diabetic patients having no DR compared to controls using SD-OCT Patients and Methods Study design: It is prospective comperative cohort non-randomized study.The study was carried out on 60 eyes of individuals collected from Benha university hospitals , ophthalmology department , in the duration between July 2016 to March 2019 .The subjects were divided into two groups:30 eyes of diabetic patients without clinical DR,30 eyes of control individuals .Both groups underwent complete ophthalmic examination including fundus examination with indirect ophthalmoscope to exclude any retinal or optic nerve diseases. SD- OCT (3D Topcon 2000) :was used to assess thickness of retinal GCC. Results There was significant decrease in GCC thickness in T1DM patients having no clinical DR compared to controls indicating retinal neurodegeneration, but no significant decrease in T2DM Conclusion Our study reports early neuroretinal changes by detecting a significant thinning of GCC in T1 diabetic patients