Diabetes incidence in an Australian aboriginal population - An 8-year follow-up study

OBJECTIVE - To examine prospectively the association between age, BMI, and subsequent incidence of type 2 diabetes in Australian aboriginal people. RESEARCH DESIGN AND METHODS - We performed a stratified analysis of inciden ce data from a community-based longitudinal study. Measures included fastin g and 2-h postload glucose concentrations, and BMI, stratified into four ca tegories. Subjects were 882 mat and female participants in diabetes screeni ng initiatives in two remote Australian aboriginal communities, free from d iabetes at baseline, ages 15-77 years. RESULTS - There were 46 incident cases of diabetes over 2,808 person-years of followup. BMI modified strongly the sex- and community-adjusted associat ion between age and diabetes incidence (P < 0.001). Adjusted for age, sex, and community the population diabetes incidence rate was 20.3 cases/1,000 p erson-years, with BMI-specific rates of 10.7-47.2 cases/1,000 person-years, and relative risks (95% CI) for BMI strata beyond the reference category ( <25 kg/m(2)) of 3.3 (1.5-7.0), 2.7 (1.1-6.8), and 4.4 (1.7-11.6), respectiv ely The population's attributable risk (95% CI) associated with BMI beyond the reference category was 70.1% (58.1-82.4). CONCLUSIONS - BMI-specific diabetes incidence rates in Australian aborigina l people art among the highest in the world. Diabetes incidence in the lowe st BMI category (10.7 cases/1,000 person-years) is two to five times greate r than corresponding rates for non-aboriginal populations. An urgent need e xists to prevent weight gain associated with diabetes. Further study is req uired to determine for aboriginal people an optimal range of BMI, likely lo wer than that suggested for non-aboriginal populations.