http://www.nature.com/nrendo/journal/v10/n10/full/nrendo.2014.144.html
The referenced articles here are an interesting set of papers studying the protective effects of autophagy on pancreatic beta cells.
My take: Fasting for up to 3 days promotes Autophagy (low Leucine, low insulin fasting - so @tdseest’s BPC sparing fast might do the trick ) and that gives our beta cells that make insulin a fighting chance.
For type 2 diabetics fasting is a tool, for up-armouring your insulin producing beta cells.