Ipomoea aquatica (IA) is a common green leafy vegetable consumed in many parts of the world. The plant is considered as a good antidiabetic herbal plant. The present work was designed to investigate the oral hypoglycaemic activity of Ipomea aquatica fractions in streptozotocin induced diabetic male rats. The male rats with average weight 200-220 g were divided into four groups (n=6), control, diabetic (induced with a single dose of streptozotocin (50 mg/kg body weight), T-1 and T-2 as treated diabetic with the two fractions of Ipomoea aquatica (IA6-1 and IA9-2), respectively. Biochemical evaluation of blood glucose, serum insulin and C-peptide were carried out. Histological examination of islets of Langerhans was done for cellular population changes. The results revealed that the oral consumption of two fractions of I. aquatica for 15 days, effective significantly reduced the fasting blood sugar level of streptozotocin-induced diabetic rats (p < 0.05). The percent changes were a 51% and 31% decrease in the serum glucose concentration of the diabetic rats when treated with the plant fractions of IA6-1 and IA9-2, respectively. Most biochemical parameters tested returned to nearly normal levels. Histologically, islets area and normal cell population were preserved in treated animals with superior results in T-1 and T-2 groups. In conclusion, fractions IA6-1 and IA9-2 showed potential antidiabetic effects when given orally to diabetic rats. The mechanism of action requires further investigation using both molecular and immunohistochemical methods investigation of both insulin secreting cells and insulin receptors. Future clinical trials could be tried using volunteers to confirm the present results so could be marketed as a supplement for diabetic patients.