Background: Type 2 diabetes mellitus (T2DM) is a metabolic disease that is lifelong and is associated with hyperglycemia, oxidative stress, and other dysfunctions of the organs. The antioxidant effect and bioavailability of selenium nanoparticles have been of interest, particularly whereby the nanoparticles have been stabilized using biocompatible polymers such as chitosan. Aim: The study in question was aimed at comparing the effects of metformin and chitosan-selenium nanoparticles (Cs-Se NPs) on biochemical and histopathological levels in an experimental model of type 2 diabetes in rats induced artificially. Materials and Methods: One hundred albino adult rats were separated into 6 groups i.e. control negative, control positive (alloxan induced diabetes), 1.5, 3 and 5mg/kg SCNP treated diabetic and a 500mg/kg metformin treated diabetic group. Alloxan was used to induce diabetes. The UV-Vis spectroscopy, XRD, FTIR, SEM, and AFM were used to characterize and synthesize Cs-Se NPs. Findings: The diabetic rats with Alloxan exhibited considerable serum urea, creatinine, liver enzymes, HbA1c, total cholesterol, triglycerides, and LDL increases and a significant decrease in HDL. Cs–Se NPs treatment caused the most significant dose-related changes in all the biochemical parameters with the dose of 5 mg/kg showing the most significant protective effects, which were similar or even more effective than metformin. Conclusion: Chitosanselenium nanoparticles are powerful antidiabetic agent, antioxidant agent, and organ-protective agent in alloxan-induced type 2 diabetic rats. The increased doses of Cs Se NPs proved to be more effective and thus it can be pointed out that they can serve as an effective nanotherapeutic approach in the management of diabetes and its complications.