Diabetes mellitus is a metabolic disorder of multiple etiology characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action, or both (WHO, 1999). These complications can be acute or chronic in nature. Acute complications include diabetic ketoacidosis, coma or death. Chronic complications include chronic kidney failure, heart disease, stroke, foot ulcers and damage of the eyes. In 2004, an estimated 3.4 million people died from consequences of high fasting blood sugar (WHO, 2009) and more than 80% of diabetes deaths occur in low and middle-income countries (Mathars and Loncar, 2006). Basically, the amount of glucose in the blood is regulated by insulin and glucagon. The hormone insulin is produced in the beta cells of the pancreas and helps the body cells especially liver, muscle and adipose tissue, to take up glucose in the blood for conversion/storage into other forms of energy for metabolic processes. Plants form the main ingredients of medicines in traditional systems of healing and have been the source for several major pharmaceutical drugs. More than 80% of the world's rural