I think the research is so limited that we just don't know until we try. Right now I'm using what I think is the highest dose that was used in the trials (10 mcg/kg/day). I guess I'd have to look into that more.
Right now, my thoughts are that it's still early, so we still have time on this dose to see an effect. Also, prolonged glucose toxicity must be playing a role, so the functionality of his exocrine pancreas is shaky. Will it heal more? Time will tell!