Objectives: Gongronema latifolium leaves have been used in folklore medicine to manage diabetes mellitus and alleviate dyspepsia. This study aimed to provide a pharmacological basis to the medicinal use of Gongronema latifolium as an antidiabetic and antiulcerogenic agent in diabetes mellitus. Methods: Ethanol extract from the leaf (200 mg/kg bodyweight) of Gongronema latifolium was administered to both streptozotocin-induced diabetic and control groups orally for 14 days. Gastric acid secretion was measured and ulcer was induced using ethanol and four-hour pyloric ligation. Results: The mean bodyweight was significantly lower (p < 0.01), while the mean weight of the stomach, liver and small intestine to bodyweight ratio was increased significantly (p < 0.05) in the two diabetic groups compared to control. Extract significantly (p < 0.01) reduced the blood glucose level similar to the non-diabetic control. Basal and stimulated acid secretion in diabetic control rats was significantly (p < 0.01) decreased when compared to control. Extract administration increased the stimulated gastric acid secretion to a level significantly (p < 0.05) higher than control while reduction in gastric secretion by ranitidine was similar compared with control. Gongronema latifolium treatment significantly (p < 0.05) reduced ulcer scores in both ulcer models and increased mucus weight in the diabetic group. Conclusion: These results suggest that Gongronema latifolium antiulcerative activity is due to its prevention of chemical-induced stomach injury.