The increasing prevalence of diabetes in South Australia: the relationship with population ageing and obesity.

OBJECTIVES: To use representative population surveillance data to monitor and project changes in the prevalence of diabetes for different age and body mass index (BMI) groups.

STUDY DESIGN: Representative, annual, face-to-face South Australian Health Omnibus Surveys, 1991-2003 (n=3000 per year).

METHODS: Trends in self-reported diabetes prevalence by age group and BMI were examined. Separate projections were made on the basis of predicted changes in population demography and diabetes prevalence.

RESULTS: The age-sex standardized absolute prevalence of self-reported diabetes among people aged 15 years and over increased from 3.5% in 1991 to 6.7% in 2003. If this current trend continues, the prevalence is expected to increase to 10.5% by 2016. The prevalence of diabetes was significantly higher among those classified as obese (6.5% in 1991 to 12.2% in 2003) than those with normal BMI. The greatest relative percentage increase in prevalence between 1991 and 2003 (169%) was seen among people aged 15-39 years. Taking both age group and BMI classification into account, the greatest relative percentage increases over this time were seen among those with normal BMI aged 60 years or older (148%), and those who were obese and aged less than 60 years (139%).

CONCLUSIONS: The prevalence of diabetes and obesity increased significantly between 1991 and 2003. Population ageing and an increase in diabetes prevalence in the future will further increase the burden of diabetes. Future increases in diabetes prevalence are not inevitable, however, if investments are made in public health prevention programmes, particularly those addressing obesity.