Diabetes mellitus is a group of syndromes characterized by hyperglycemia which could be managed and controlled through medication and Insulin The current advocacy of intensive insulin therapy regimens involving multiple daily subcutaneous injections places a heavy burden of compliance on patients and has prompted interest in developing alternative, less invasive routes of delivery. The oral route is considered to be the most convenient and desired route of drug delivery which will help eliminate the pain caused by injection, psychological barriers associated with multiple daily injections and possible infections. Oral delivery of Insulin as a non-invasive therapy for Diabetes Mellitus is still a challenge to the drug delivery technology, since it is degraded due to the presence of enzymes in the acidic environment of stomach and also its absorption through the gastrointestinal mucosa is questionable. In developing oral protein delivery systems with high bioavailability, various practical approaches might be most helpful like protecting insulin from enzymatic degradation, use of penetration enhancers , chemical modification, Bioadhesive delivery system, use of microspheres and nanoparticales to improve bioavailability of insulin. Despite, various techniques each having its own limitation and advantages, the oral route scores over the others for the ease of comfort with which the therapeutic agents can be administered to the patients work on attempts to deliver insulin orally has definitely gathered momentum and is no longer considered with pessimism to develop the oral insulin drug delivery system.