Diabetes mellitus is a group of metabolic disorders characterized by chronic hyperglycemic conditions resulting from defects in insulin secretion, insulin action or both. It is a growing public health concern world wide affecting humans and animals. Synthetic drugs available for the management of the ailment have serious adverse side effects, complicated mode of intake and are expensive. Natural products such as plants have been used since prehistoric era for management of the disease. However, the effects of such natural products are not standardized and are either under reported or exaggerated. In this study, we isolated and characterized anti-diabetic principle present in Cussonia arborea root bark extract. Haemato-biochemical changes associated with its therapy in alloxan-induced diabetic rats were also investigated. Results of treatment of diabetic rats with extracts of Cussonia arborea revealed significant hemato-biochemical ameliorative potentials on the diabetic rats.