Type 2 diabetes and impaired glucose tolerance in aboriginal populations: a global perspective.

OBJECTIVE: To perform a systematic review of the prevalence of type 2 diabetes and impaired glucose tolerance (IGT) in aboriginal populations worldwide. RESEARCH DESIGN AND METHODS: A Medline search from 1966 to 2005 was conducted. Studies were selected if they utilized accepted diagnostic criteria for type 2 diabetes. Year of study, sample size, response rate, age range, and prevalence of type 2 diabetes and IGT were documented.
RESULTS: Forty-two studies were selected, comprising 59 populations. Although the majority demonstrated a several-fold elevation of type 2 diabetes prevalence as compared to non-aboriginal populations, this was not a universal finding; a small number of populations studied actually had a low prevalence of type 2 diabetes and IGT. Lower prevalences were found in rural compared with urban populations. Interestingly, we were also able to document an inverse relationship between the ratio of IGT/type 2 diabetes and type 2 diabetes prevalence. These data are consistent with the hypothesis that those populations with the very highest rates of type 2 diabetes appear to have progressed past the prediabetes stages in the natural history of this metabolic disorder.
CONCLUSIONS: Type 2 diabetes and IGT prevalence rates vary widely amongst the world's aboriginal populations. Despite very different histories and cultures, the consequences of rapid changes in nutrition and exercise appear to have very similar metabolic consequences on aboriginal populations, the magnitude of which may be determined by the strength of the genetic susceptibility.