Abstract: Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia that results from abnormal secretion of insulin, inappropriate action of insulin or both. The aim of this study is to determine the effects of exenatide and sitagliptin treatment on the expression of insulin (INS-1), insulin receptor (INSR) and insulin receptor substrate (IRS-1) genes. In this study streptozotocin-induced diabetic rats were treated with sitagliptin (10 mg/kg) and exenatide (0.1 µg/kg) for 15 days. We measured INS-1, INSR and IRS-1 gene expression levels and examined the histology of pancreatic tissues in all groups. Exenatide and sitagliptin treatment increased gene expression levels of INS-1, INSR and IRS-1.