You would think with as advanced as medicine has become they could do this. Or perform a pancreas transplant by now! Priorities are askewed when we are more concerned with what high tech gadget we can produce than pouring that kind of determination into medical break throughs!!
From my experience that is the reason is because your lacking that so there is no real way to make it do it's job other than doing it for it that's why I call an insulin pump a pancreas or a techno pancreas because it is just like having a transplant but your not taking anything out you are just adding a smart box to your belt