I recently read an interesting article at
www.reversingdiabetes.org that basically blames the use of cow's milk for nursing babies instead of mother's milk as the primary cause of Type I diabetes.
Apparently, according this article, there is a protein in cow's milk that makes the body's immune system create antibodies and in some people, this particular protein is also found in beta cells. The antibodies attack the beta cells and destroy them. According to the article, there is a direct correlation between the use of cow's milk and Type I diabetes. They state the countries that have the highest incidence of Type I are also the same countries that have the highest incidence of cow's milk use.
I found it interesting and at least plausible.