Diabetes is an autoimmune disease (source: am diabetic) so this is probably not a viable long term solution
The mice they have been testing have maintained their glucose at human levels for months (they generally run 60-80 points higher than humans). They've binged and fasted them, made them sick and everything and their levels have maintained.
This is definitely promising, don't be such a wet blanket before researching a little bit!
This is a very incredible result though. Even if immunosuppressants are required, think of all the non-patient outcomes: easily sourced human SC-beta cells for research and high throughput study. This stuff can be grown at volume, and the techniques will only improve. The results will also inform research into other cell lines. Bottom line, this is yet another step forward for stem cell tech.