Cerium oxide nanoparticles (CNPs) as an antioxidant have been used frequently to attenuate hyperglycaemia oxidative damage in different organs. We investigated the impact CNPs on the qualitative and quantitative sperm parameters, spermatogenesis and NFE2‐related factor 2 (Nrf2) expression as a major contributor of antioxidant defence in the male diabetic rats. Twenty‐four male rats were divided into four groups. Controls received only mouse food and water. Second group were treated with CNPs (30 mg kg⁻¹ day⁻¹) for 2 weeks. Rats in third group received streptozotocin (STZ) (60 mg/kg). In fourth group, animals became diabetic and received CNPs (30 mg kg⁻¹ day⁻¹) for 2 weeks. The results showed a significant abnormality in the sperm parameters and histopathological patterns of testes in the diabetic group compared to the control group and CNPs treatment significantly improved all testicular parameters. Following CNPs administration, sperm DNA fragmentation significantly reduced in the STZ‐treated rats. Moreover, after CNPs intake in the STZ‐treated rats, Nfr2 expression levels increased significantly. Overall, CNPs administration on the diabetic rates can attenuate detrimental effects of diabetes on the sperm potential fertility, sperm parameters, DNA integrity and Nrf2 expression levels. This study gives a future prospect to determine the role of CNPs in the context of diabetes.