Both types of diabetes mellitus (DM) are recognized by the destruction of pancreas or deficient function of Islets’ cells causing several complications. Diabetes mainly affect the kidney leading to diabetic nephropathy (DN) in the late renal stage, which caused higher mortality in diabetic patients. Since diabetic disease appearance, nephropathy may be observed in patients with type 1 or 2 diabetes. Recently, cell culture can be used in the regenerative medicine as a new method for treating diabetes and DN. Therefore, the aim of the current study was to prove the beneficial effect of mesenchymal stromal cells (MSCs) transplantation on DN during the early stage. Male rats were randomized in 3 groups (each 20 rats): the 1st group was normal rats, while the 2nd was streptozotocin (STZ) diabetic rats and the 3rd was diabetic rats treated with a single intravenous dose of bone marrow mesenchymal stromal cells (BM-MSCs) after 3 days from STZ induction. Results indicated that STZ induced DN represented by weight loss, hyperglycemia, hypoinsulineamia, decreased glycated hemoglobin, leukocytosis and impairment of kidney function and oxidative stress in kidney tissue. After BM-MSCs treatment, blood glucose level was improved, renal function was retained, body weight loss was decreased, insulin level and HBA1C percent were ameliorated with improved oxidative stress in kidney tissue. BM-MSCs have the capacity to regenerate and differentiate into insulin- producing cells improving DM and DN