Research on oral delivery of insulin has been carried out for a number a years. Insulin is usually administered as subcutaneous injections. In case of therapeutic proteins such as insulin, oral delivery method requires the development of special formulation and advanced drug delivery system because of its rapid acidic degradation in the stomach, inactivation and digestion by proteolytic enzymes in gastrointestinal tract and poor permeability of large molecule across intestinal epithelium to bloodstream which results in low bioavailability of insulin.

In the present article some problems pertaining to oral insulin delivery and relevant solutions have been described. The article describes also the characteristic features of oral insulin products which are now undergoing preclinical and clinical tests. Many pharmaceutical companies worldwide are working on the potential administration of oral insulin. Currently, two oral insulin products are at the advanced stage of clinical trial, i.e. IN-105 – PEG-ylated insulin (Biocon) and HDV-I – liposomal insulin (Diasome).