Well, as I see it In mathematics generalizing is exact and in physics, precision allows generalization, as it deals with measurements. Of course, I can be wrong.
About Southeast Asian populations. On average, is due to low muscle mass and higher abdominal fat. This leads to insulin resistance more easily.
The Ethno-phenotypical traits are thought to have been selected for cold climates where fat based diets are preferred.
http://asiandiabetesprevention.org/what-is-diabetes/why-are-asians-higher-risk