The effect of the leaf extract of Naringi crenulata in normal and streptozotocin (STZ) induced diabetic rats were studied. Blood glucose levels were determined after oral administration of graded doses of Naringi crenulata (300, 600mg/kg) in fasted normal and diabetic groups. In both groups, 600 mg/kg of the extract, significantly reduced blood glucose levels 8 h after administration, which was consistent and time-dependent. The higher doses of 300 mg/kg did not affect significantly the blood glucose levels. The plant extract (Acetone) is given to the diabetic rats as well as normal rats orally by intragastric tubes. The blood glucose levels were increased when diabetes is induced in all the experimental rats. The methanolic extract of N. crenulata action was significant in increasing the plasma insulin levels in diabetic rats when compare to acetone extract treated rats. Total Hb was also found increasing in extract administered rats. The normal rats blood glucose levels did not change much when treated with plant extract alone. The plant extract was capable of ameliorating at the glycosylated Hb levels and moderate increase in glycogen levels and significant decrease in urea and creatinine levels while administering deferent dosage of N. crenulata extracts.