Background : Diabetes mellitus is known as a major worldwide complication. Despite numerous synthetic medicines presented for treatment of the disease, it still remains a universal health problem. Although Citrullus Colocynthis is traditionally used as an antidiabetic herbal medicine, however, scant studies describe the antidiabetic properties of the fruit. The present study was designed to investigate the probable hypoglycemic effects of this drug in diabetic rats.

Materials and Methods : This work was carried out on 15 male (n=7 and n=8 in the control and test groups, respectively) Wistar rats weighed 200 – 250 g. To make the animals diabetic, they were injected by a single dose of streptozotocin. The rats in the test group were treated daily (continued for 40 days) by the herbal medicine (30 mg/kg dissolved in 0.2 cc distilled water), while those in the control group received distilled water in the same volume. Plasma glucose was measured 10, 20, 40 days following the prescription and 10 days after the termination of treatment.

Results: We found a significant decline in the plasma glucose of the drug-treated rats on the 10th day of experiment (P<0.05). In contrast to the control group, the number of diabetic rats decreased in the drug-treated group with passing the time (P<0.018). While the mortality rate decreased in the rats treated with the medicine, it considerably increased in the controls as the experiment proceeded (P<0.05).

Conclusion : Citrullus Colocynthis has a moderate hypoglycemic effect in adult diabetic rats. Decreased number of diabetic animals and increased mortality in the test animals indicate that the herbal medicine has a potential effect in treating diabetes.