Dr. Monte gives his references for Type I diabetes
714 &
715
and notes the possibility that early "allergy" to milk might be the culprit.(p.172Ch10) There are, unfortunately, some identifier tags on cow's milk protein and on cells of the Islets of Langerhans that happen to be identical. So there is a possibility that giving cow's milk to infants too early, before gut closure, might induce (true) autoimmune response and thereby early removal of the insulin producing cells.
With just a little more digging it seems to me that this possibility becomes a conclusion. Type I diabetes has been
increasing exponentially since 1900.
That is the same start date as the
first mass marketing
of a dairy product given to infants (condensed milk).
Todays mass marketing of infant formula has grown to universal acceptance. In the US 38% of women are breastfeeding exclusively at three months and only 16% at six months.ref
In China only 15% breastfeed exclusively initially, and there is a huge desire for western-brand formula.ref,refb
Except for one, all brands of US infant formula include cow's milk.
It's a separate issue, but probably worth recalling that the US exports powdered formula to undeveloped countries known to have problems with water sanitation.