It is known that oxidative stress plays an important role in the chronic complications of diabetes. Lipid peroxidation is one of the consequences of oxidative stress. Erythrocyte deformability abilities are reduced as a result of lipid peroxidation. Conversely, a decrease nitric oxide (NO) production seems to be responsible in endothelial dysfunction which occurs in diabetic vascular complications. Carnosine is a molecule with anti-oxidant properties. The aim of this study was to investigate erythrocyte deformability indices and the effects of carnosine on erythrocyte deformability in diabetes and to determine a possible relationship between carnosine and nitric oxide. Male Wistar albino rats were used in the study. Injections were administered to seven groups consisting of eight rats each. The groups were: Control, Carnosine, L-NAME (NG-nitro-L-arginine methyl ester), Diabetic, STZ (Streptozotocin)+Carnosine, STZ+L-NAME and STZ+Carnosine+L-NAME. In addition, glucose, insulin, MDA (Malondialdehyde) and NO levels were measured and erythrocyte deformability indices were calculated in all groups. Erythrocyte deformability indices and NO levels were decreased and MDA levels were found to be increased in diabetic group. It was also found that carnosine can significantly reverse erythrocyte deformability, reduce lipid peroxidation and increase NO levels in diabetes. It can be concluded that carnosine can recover from microvascular circulation problems by increasing erythrocyte deformability, can protect cells and tissues against lipid peroxidation and can be used as a multi-functional antioxidant in the treatment of diabetes mellitus to prevent the complications of diabetes.