Background and Objectives: Diabetes is one of the major health challenges in world. Herbal medicines are widely used for the treatment of diabetes. The current study assessed the effects of oral administration of essential oils from Myrtus communis, Trachyspermum copticum and Ferula gummosa on blood glucose and lipid profiles in streptozotocininduced diabetic rats and inhibitory effects of these oils on α-glucosidase activity in vitro. Materials and Methods: Forty-eight male Wistar rats were divided into six groups of healthy control, diabetic control, healthy control received corn oil and three experimental diabetic groups treated by the essential oils. Four weeks after intraperitoneal injections of 45-mg/kg streptozotocin doses, experimental groups were gavaged with 200 mg/kg/day of the oils for thirty days, then serum glucose and lipid profiles of the rats were assessed. Data were analyzed using one-way ANOVA and Tukey test. Study was carried out in Animal Laboratory of the