The present study was carried out to explore a novel strategy with the hypothesis that the combined treatment with standard antidiabetic drug metformin (MET) and chitosan stabilized nanoparticles (CTS-Se-NPs) may have a potential role on insulin level, hepatic damage and apoptosis, and cardiac injury markers of type 2 diabetes mellitus (T2DM) in rat model. T2DM was induced by a high fat diet (HFD) for 8weeks and a single injection of a low dose streptozotocin (STZ) (35mg/kg) in Sprague Dawley rats. A total number of one hundred rats were divided into five groups; the first served as a control (non-diabetic) group and the other four groups served as diabetic rats. The treatments were even mono or combined therapy by CTS-Se-NPs and/or MET for 8weeks. A group was given only MET (500mg/kg bw/day), another was administered only CTS-Se-NPs at a dose of 2mg se/kg/day, while the last group was given both of them (co-treated group). Biochemical, molecular and histopathological analyses were conducted to figure out the efficiency of the treatment by the monotherapeutic mode or combination therapy on the insulin level, oxidants/antioxidants status, inflammatory mediators, hepatic and cardiac injury biomarkers and apoptotic/anti-apoptotic gene expressions. Our results indicated that HFD/STZ-induced toxic effects on the serum, hepatic and cardiac tissues including a remarkable elevation of the oxidative and inflammatory mediators, and up-regulation of the apoptotic genes (Bax, Caspase-3, Fas, Fas-L) expression. Histologically, the heart tissue revealed various degenerative, vascular and inflammatory alterations characteristic to murine cardiomyopathy. Besides, livers from HFD-STZ-treated rats showed numerous cytotoxic, circulatory and inflammatory alterations. Combined therapy with MET and CTS-Se-NPs resulted in a better remarkable anti-diabetic effect demonstrated by substantial decreases in fasting blood glucose and insulin levels, and elevated with up-regulation of anti-apoptotic gene (BCL-2) and down-regulation of apoptotic genes after 8weeks of treatment than that revealed in the monotherapeutic strategy. In addition, it ameliorated the damage of cardiac and hepatic tissues and reduced lipid accumulation, and pro-inflammatory cytokines levels and restored the antioxidant capacity. It could be concluded that, the combined strategy applied in the current study have a potential role to limit the diabetic complications and restore insulin resistance to a higher extent than monotherapeutic strategy and could be considered a promising therapeutic alternative in T2DM rat model.