Introduction: Diabetes is a combination of carbohydrate metabolic disorders in which glucose is consumed less and causes hyperglycemia. Postprandial hyperglycemia is known as the main side effect of diabetes 2. The Quercus infectoria is a fagaceae,s family of plants that has therapeutic effects on astringent , antidiabetic, antifungal, antimicrobial, local anaesthetic and antiinflammatory. In the present study, for the first time, the effect of ethanol extract of the acorn inner bark on postprandial blood glucose level in normal and deiabetic male rats was studied.

Matherials & methods: 88 Wistar male rats weighting 250-300gr were randomly divided into five normal and six diabetics were exposed by streptozotocin. The doses of 500 mg/kg and 1000 mg/kg of the extract and 5mg/kg acarbose in the form of gavage and dose of 250mg/kg extract in the form of gavages and   intraperitoneal intragastric injection along with intragastric injection of maltose 2 gr/kg were studied. Blood glucose level was measured by glucometer at zero times (before injection) and also 30, 60, 120 minutes after injection.

Findings: In normal and diabetic rats the different doses of the extract comparing with the control group caused a significant reduction of postprandial glucose. In normal rats 250mg/kg dose was   more effective in comparison with acarbose 5mg/kg. In diabetic rats the injection of intraperitoneal extract was as effective as gavage injection in lowering postprandial blood glucose.

Discussion & Conclusion: Intraperitoneal extract injection was as effective as gavage injection in lowering blood glucose hence, it shows that it would be probable that the effectiveness of the extract is formed by increasing the sensitivity of the cells to the insulin.