Earlier quoted context omitted.
Viruses themselves are a common cause of autoimmune reactions that cause T1D. Attempting to automatically blame a vaccine for a virus that commonly affected youth with little to no sign of infection probably isn't a very scientific method of determining cause.
Article notes that coronaviruses binding to ACE2 receptors in the pancreas could cause this. Binding to ACE2 receptors is done by the spike protein, the same spike protein the vaccines created mass amounts of.
The question would be if vaccine followed by covid infection produced more or less spike proteins (and overall health impact) than no vaccine followed by covid infection.
If you assume that hospitalization and death is correlated to overall quantity of damaging spike proteins then the default assumption would have to be that vaccines are highly beneficial.