FIGURE 1. Age-standardized prevalence of type 2 diabetes mellitus.

Among the main features are the low prevalence among groups of European origin, especially those remaining in Europe; the high prevalence among Pima Indians and urban New Guineans, and among Nauruans today; and the higher prevalence in urban or westernized groups, compared with their rural or traditional counterparts. Because type 2 prevalence in a given population increases with age, it would be misleading to compare raw values of prevalence between two populations that differ in their age distribution; the raw values would be expected to differ merely as a result of the different age distributions, even if prevalences at a given age were identical between the two populations. Instead, one measures the prevalence in a population as a function of age, then calculates what the prevalence would be for that whole population if it had a certain standardized age distribution³⁰. (From refs 5, 30 and other sources.)