Stimuli-responsive polymers for treatment of diabetes mellitus

Abstract Diabetes mellitus is reported as one of the most severe and lethal diseases in the world, formed by the accumulation of glucose in the blood and the number of diabetic patients will be going to cross ~ 552 million by 2030. However, after so many innovations and discoveries, insulin is the only drug used to maintain blood glucose levels and gives prolong lives to the diabetic patients. The traditional administration of insulin was based on frequent subcutaneous insulin injections which have certain side effects like pain, infection, local tissue necrosis, and nerve damage. Therefore, the fabrication of self-regulated insulin delivery systems which can automatically regulate the amount of insulin released according to the change of blood glucose level is in high demand. On this context, stimuli-responsive systems have gained attention of researchers due to their less side effects and improved efficacy. Stimuli-responsive polymers have the ability to respond to a certain external environmental changes (termed as “stimulus”) by altering some of their physical and chemical properties. For insulin delivery, the majority of the stimuli- responsive system lies on the change in pH and/or glucose concentration; however, recently, some of the temperature, electrochemical, and redox-responsive polymeric systems were reported. These systems show rapid change in their structure and/or respond with respect to the variation in pH, temperature, glucose concentration, etc., so that rapid release of insulin can take place. This chapter is an effort to combine the past, present, and future of the stimuli-responsive polymer-based drug delivery system for treatment of diabetes mellitus in a simplest way.