Oral insulin delivery: utopia, currently possible or a near reality?

Diabetes is still one of the main diseases worldwide due to its high incidence, prevalence and, unfortunately, very high mortality. Type 1 diabetes (and in some other types) is generally controlled by exogenous insulin. Several attempts of oral insulin administration to humans have been done so far. Some of them achieved interesting results, but it seems to exist a barrier to transpose these studies into clinical trials. A broad perspective...