The present study investigated the effects of selenium nanoparticles (SeNPs) at dose 2 mg/kg body weight in streptozotocin (STZ) induced diabetes in a rat model at dose 50 mg/kg body weight. Rats administered SeNPs orally in normal and experimentally induced diabetic rats for 35 days and glibenclamide (Glib)at the dose rate of 20 mg/kg was used as a reference drug. Blood samples were collected at the end of experimental. administration of SeNPs was significantly decreased blood glucose levels and enhanced serum insulin concentration, Result showed decrease liver function enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), all groups results showed non-significant changes in serum creatinine levels, decrease cardiac function enzymes creatine kinase-MB (CK-MB). Result also showed significant decrease in the activity level of α-amylase. Also, Glib administration also exhibited a significant improvement in diabetic animals after 35 days of treatment. This study suggests that SeNPs capped with chitosan can alleviate hyperglycemia and showing synergistic effect in STZ-induced diabetic rats and these protection may be possibly by eliciting insulin-mimetic activity or SeNPs showed enhancement of the elimination of the diabetes-induced oxidative stress injuries.