The present study was designed to investigate the protective, and curative potentials of Moringa oleifera (MO) leaves powder against streptozotocin (STZ) induced type 1 diabetes mellitus (T1DM) in rats. Fifty adult Wistar male albino rats were randomized and divided into five equal groups: The normal control group, the Moringa group, The diabetic group, the therapeutic group, and the diabetic rats (3 days after STZ injection) were received-MO-for successive 8 weeks and the prophylactic group, the rats were received-MO-for 2 weeks before STZ induced diabetic rats and lasted for 8 weeks. The protective or treated oral administration of 1 ml freshly prepared aqueous leaf decoction of-MO-revealed a significant upregulation of the mRNA expression of PDX-1, Ngn3, VEGF, IGF-1, and GLUT-2. Additionally, it induced a significant downregulation of FBG level compared to that of the diabetic group, a significant reduction in MDA level and a significant elevation in the TAC level. Furthermore, the histopathological observations of pancreas, liver, and kidney tissues affirmed the improvement in treated and prophylactic groups compared to STZ-diabetic groups, and the improvement in the prophylactic group was more distinct than the treated group. MO-aqueous leaf extract can treat and protect against STZ-induced T1DM; via its antioxidant action (increase the TAC and decrease MDA). Thus, it has the potential for utilization as a prophylactic against diabetes.