The attempt to design oral formulations of insulin has been a cutting-edge area of interdisciplinary research where chemical, pharmaceutical, and biological sciences have joined hands to provide a sustainable solution to diabetic patients. This chapter presents an overview of diabetes highlighting various aspects of insulin therapy, including insulin analogs, oral delivery of insulin, mechanistic action of insulin, challenges of oral administration of insulin and breakthroughs in insulin delivery at the global level. This chapter also provides an account of commercialization level of insulin.