One key thing to note is that it is a US based study.
Because TB isn’t common in the U.S., children here do not receive the vaccine.
In the UK, I had the BCG vaccination; I think that this is still common?
Ah!
https://www.nhs.uk/conditions/vaccinations/bcg-tb-vaccine-questions-answers/.
The BCG is no longer offered to children in secondary schools in the UK. It was replaced in 2005 with a targeted programme for babies, children and young adults at higher risk of TB.
also
The BCG vaccination is thought to protect up to 80% of people for up to 15 years.
which makes me wonder why adults don't/didn't get a booster. I was done as a teenager at school (assume aged 15) so I should have had a booster at 30 and 45 to maintain my immunity if the vaccine only lasts 15 years.
However prior to 2005 there must have been T1s in the UK who had the BCG vaccination without being cured of diabetes, although I also note that
While it took three years for patients to see results from the vaccine, two doses of the drug spaced four weeks apart were still having a lasting impact eight years later.
so even if there was a response nobody would have tied it in with a vaccination taken 3 years ago.
If I was cynical I might think that this research was part of trying BCG on everything from piles to ingrowing toenails to the common cold because widespread use seems to be eliminating TB from many countries which are then stopping mass vaccinations. An indication that the vaccination is so good that it is destroying not only TB but its own market.
Still, if this is anywhere near accurate then it could be a big result for T1s and presumably also for at least some T2s.