Oral delivery of insulin is one of the most promising and anticipated areas in the treatment of diabetes, primarily because it may significantly improve the quality of life of diabetics who receive insulin regularly. Several problems have been reported regarding the subcutaneous delivery of insulin, ranging from cardiovascular complications to weight gain. One of the approaches to overcoming these issues is to administer insulin through the oral route. However, there are several challenges in developing an oral route for insulin delivery; insulin has extremely poor bioavailability and a low diffusion rate through the mucus layer. A wide range of oral insulin delivery techniques have recently been researched, ranging from nanoparticles to liposomes, self-emulsifying systems, and hydrogels. These techniques have shown promising potential in the oral delivery of insulin. This review considers the current literature on the advances and challenges in the development of oral insulin.