Over the last 50 yr, changes in lifestyle have led to a dramatic increase in the prevalence of type 2 diabetes
in virtually every society around the world. Reductions in physical activity, increases in dietary intake, and the
aging of the population are key factors in bringing about this rapid change. The westernization of diet and of
other aspects of lifestyle in developing countries has uncovered major genetic differences in the susceptibility
of different ethnic groups to type 2 diabetes. This is most readily apparent in Pacific islanders and indigenous
populations in North America and Australasia, among whom type 2 diabetes has gone from being almost unheard
of 100 yr ago, to affecting up to 30% of the adult population today. As the prevalence of type 2 diabetes has
increased, the age of disease onset has also decreased. The traditional paradigm of type 1 diabetes affecting
children or young adults and type 2 diabetes affecting the middle-aged and elderly is starting to change. The
increasing numbers of young adults, and even children, who are presenting with type 2 diabetes is blurring the
distinction between the 2 types of diabetes and heralds a much longer time for people with type 2 diabetes to
develop debilitating complications.
This chapter will describe the epidemiology