i wonder if it (diabetes) was as prevalent in say the 1800's as it seems to be today, with like you say all the white starches.
Ya know, that's a great question. Without having statistics handy (and I'm not sure there are any statistics for this), I'd tend to think that the diabetes "epidemic" today in america is related not only to the obesity problem, but also to diet. The same might be said, I'd imagine, for all of these weird auto-immune diseases, etc. that seem to be popping up all the time. I'm sure some or a lot of it is related to environmental factors--e.g., one prominent theory about the cause of MS, or at least ONE cause of it, is over-exposure to radon.
The glycemic index stuff is pretty interesting, and I wonder if that explains anything about the diabetic phenomenon today. From what I know (not from personal experience, but from a family member), the less serious kind of diabetes can be regulated in part by diet and by careful attention to the glycemic index. That would lead me to believe that it is also caused by diet, or that diet is a big factor.
This is pretty scary, and I don't know if it's true, but I've read somewhere that with all the white-flour based foods the average American eats today, by the time we're in our early 20s, our intestines are literally coated with a layer of floury-type gunk.