See https://www.bmj.com/content/362/bmj.k3547
The incidence of type 1 diabetes is highest in countries following a western lifestyle and, until recently it has been increasing at a rate of 3-4% per year, especially in children below 5 years of age in Europe. This increase is faster than can be accounted for by genetic drift, pointing to the importance of environmental factors.
Now go and read the rest of the paper for yourself.