An overview of natural polymers for oral insulin delivery

► Diabetes mellitus, one of the expensive health problems in the world is increasing in prevalence. ► Exogenous administration of insulin is the only treatment option available for diabetes mellitus patients other than lifestyle modifications. ► Oral route is the most preferred and convenient route for the administration of insulin. ► Use of polymeric matrices (both natural and synthetic) as carriers remains one of the most promising strategies for oral insulin delivery. Current therapy for diabetes mellitus through oral anti-diabetic drugs and subcutaneous administration of insulin suffers from serious disadvantages, such as patient noncompliance and occasional hypoglycemia. Moreover, these approaches doesn’t mimic the normal physiological pattern of insulin release. Oral route would be the most convenient and preferred route if it is available. Polymeric nano and/or microparticles, either natural or synthetic have been used as matrices for oral insulin delivery. Natural polymers are of particular interest due to their nontoxic, biocompatible, biodegradable and hydrophilic nature. Among the natural polymers used for oral insulin delivery, chitosan (CS) is widely explored owing to its ease of chemical modification and favorable biological properties. In addition, many advantages such as safety, biodegradability, widespread availability and low cost justify the continuing development of promising insulin delivery system based on CS.