Background: The major concern in diabetes is increased oxidative stress. Maintaining a balance between reactive oxygen species (ROS) and antioxidants is a major mechanism in preventing damage from oxidative stress. Quercetin (QR) is a well-known flavonoid and a strong antioxidant derived from the onion, Allium cepa, and it has been shown to reduce oxidative stress in the long-term treatment of streptozotocin (STZ)-induced diabetes in animals.

Objective: We aimed to study on beneficial effects of QR & Allium cepa on regulation of blood glucose in diabetic model.

Methods: Seventy male 8-week-old Wistar albino rats weighing 250 ± 10 g were obtained, the rats were divided into seven groups comprising ten animals in each group. Diabetes induced with single intraperitoneal injection of STZ. Diabetic rats treated with quercetin (15mg/kg/day, started 48 hours after STZ injection) and Allium cepa juice (2cc/rat/day, started 48 hours after STZ injection). After 28 days treatment, analysis on blood glucose and insulin was done.

Results: The mean TAC showed a significant increase (p < 0.05) in the QR compared to the control, STZ and STZ + QR groups. Both QR and onion Juice had significant effect in lowering blood glucose (355.3 ± 104 mg/dl and 353.4 ± 103 mg/dl respectively) (p<0.05) in STZ induced diabetic animals. Both QR and onion juice had lowering effect in Serum insulin in healthy animals and significant increasing effect on serum insulin level in diabetic animals.