ABSTRACT Introduction: Mirabegron is a novel beta-3 receptor agonist. It has potential antiobesity and antidiabetic effects. The aim of the study was the evaluation of the possible antidiabetic, anti-inflammatory and antioxidant effects of mirabegron as well as its effect on serum leptin and adiponectin in diabetic rats alone and in combination with sitagliptin. Materials and Methods: Five groups of Wistar rats were used. Diabetes was induced in group 2, 3, 4 and 5 using streptozotocin in dose of 100 mg/kg. The third, fourth and fifth group were treated for 20 days with sitagliptin (10 mg/kg), mirabegron (10 mg/kg) and combination of the 2 drugs, respectively. Blood samples were used for determination of blood glucose, serum level of leptin, adiponectin, TNF-α, malondialdehyde (MDA) and glutathione (GSH). Results: Streptozotocin caused induction of type-2 diabetes, increased TNF-α and MDA with reduction in the leptin, adiponectin and GSH. Sitagliptin caused a significant reduction of blood glucose, TNF-α and MDA with significant increase in leptin, adiponectin and GSH. Mirabegron caused a non-significant reduction of blood glucose, TNF-α and MDA with significant increase in the leptin and GSH. There was non-significant difference between the effect of the combination of sitagliptin and mirabegron and the effect of sitagliptin alone. Conclusion: Sitagliptin has a moderate anti-inflammatory and antioxidant effects. Mirabegron has a modest antidiabetic, anti-inflammatory and antioxidant effects and failed to normalize the low serum levels of leptin and adiponectin of streptozotocin induced diabetic rats. The addition of mirabegron to sitagliptin shows no additional or synergistic effects.