Extensive research has been carried out for developing nanocarriers to overcome the major barriers preventing success in oral insulin therapy, which includes (a) identification of in vivo barriers, (b) incorporation of prerequisite characteristics into single nanocarrier, and (c) exclusion of the use of additional potentially toxic chemicals as enzyme inhibitors or permeation enhancers. The present review identifies the prerequisite characteristics of single nanocarrier that could avoid major hindrance being faced in oral insulin delivery. An effort is made to discuss the involvement of prerequisite characters to overcome the major hurdles, which prevent the success in oral insulin delivery.