The cornea exhibits viscoelastic properties, which give it the quality of hysteresis. Corneal hysteresis is an important indicator of the biomechanical properties of the cornea. The aim of our study was to show the impact of diabetes on corneal biomechanics. We used the Ocular Response Analyzer device which measures CH, CRF, IOPcc and IOPg to detect the changes that occurred in corneal parameters of the patients with type 2 diabetes since hyperglycemia in diabetic patients alters the corneal structure by impairing the hydration of the cornea and homeostasis in the corneal epithelium, stroma and endothelium. We conducted our study on control and diabetic patients to detect the relation between diabetes mellitus and the corneal biomechanics. Our study was performed on 80 eyes of 44 patients as we divided these patients into two groups. Group A involved 40 eyes from 20 healthy control subjects and group B involved 40 eyes from 22 diabetic patients. Our study reported that diabetes leads to an increase in corneal biomechanics as CH and CRF were elevated with patients of group B (diabetic patients). Our explanations to those results were due to hyperglycemia, as glucose accumulates in collagen proteins resulting in the formation of covalent cross-linking bonds which lead to increased corneal thickening. Most probably the patients with hyperglycemia (elevated HbA1c) showed increase in corneal damping. This increased damping effect was reflected in a higher CH. Meanwhile our study correlated both CH and CRF to the duration of diabetes mellitus and HBA1c in both study groups to show the effect of diabetes on corneal biomechanics. Our results revealed a weak positive linear correlation between the CH and the average duration of diabetes in diabetic group and no correlation between CH and the average level of HBA1c in control group. However there was a weak positive linear correlation between CH and the average level of HBA1C in the diabetic patients in the diabetic group. For CRF there was a weak positive linear correlation between it and the average duration of diabetes mellitus in diabetic group and there was a very weak negative linear correlation between it and the average level of HBA1c in control group patients. However, the correlation between it and HBA1c in diabetic group was a moderate positive linear correlation.