This is a nifty little animation about China's population. Apparently they are slowing down with the wee ones. I would imagine as they become "more developed" or "get richer" the birth rate will continue to go down. The same thing will probably happen in India.
http://www.iiasa.ac.at/Research/LUC/...im/pop_ani.htm
Curing diabetes will probably help the most in North America, where all the fatties live. We'll have a lot of old fat people.