That's an excellent question.
It seems that type 1 diabetes prevalence is highest in countries in sort of temperate climates in northern hemispheres. You also see it very high in Scandinavian countries and in Sardinia, interestingly. Canada is, I think, seventh worldwide.
The increasing prevalence of type 1 diabetes is going along with other autoimmune diseases, as well, that tend to be on the rise. There are a number of theories for that. Our genetics haven't changed that much over the years, so it's thought that it's maybe some environmental trigger like a virus or something that could initiate the autoimmune response.
In the case of autoimmune disease and type 1 diabetes specifically, one of the hypotheses out there is a hygiene hypothesis, and that we now grow up, our kids grow up in an environment that is much cleaner than the ones we grew up in as kids. I'm speaking about us older folks who played in the sandbox and got a bit dirtier. There may be something that goes on with sort of the gain setting of the immune system, the sensitivity.
What goes wrong in autoimmune disease is the recognition of self. The immune system fails to realize that the insulin-producing beta cells are its own cells and it attacks them as though they're an infection, a bug or a virally infected cell. One hypothesis is that in this cleaner environment we grow up in now, because of better antibiotics and the like, more antiseptic procedures and general cleanliness, we are more prone to the development of autoimmune disease when it's triggered by whatever that trigger may be.