Australia sees a decline in type 2 diabetes, but disparities persist

New study reveals a decade-long decline in type 2 diabetes across Australia but warns of surges in younger men and specific ethnic populations, urging targeted prevention efforts.

Study: Changes in the incidence of type 2 diabetes in Australia, 2005–2019, overall and by socio‐demographic characteristics: a population‐based study. Image Credit: Halfpoint / Shutterstock

In a recent study published in the Medical Journal of Australia, researchers from Melbourne investigated the trends in incidence rates of type 2 diabetes in Australia from 2005 to 2019. They examined overall trends and variations by age, sex, country of birth, socioeconomic status, and geographic remoteness. The study also explored shifts in diagnostic practices and their impact on reported trends. They discussed demographic disparities and the evolving dynamics of diabetes diagnosis within the Australian population.

Background

Type 2 diabetes has rapidly become a significant global public health concern, with its prevalence and incidence varying widely across regions and populations. While prevalence is commonly used to assess the burden of diabetes, it can be influenced by mortality rates and does not directly indicate population risk. Incidence rates offer a clearer picture of new cases and emerging trends.

While existing research has highlighted the differences in diabetes incidence by ethnicity and socioeconomic factors, studies continue to face limitations such as small sample sizes or lack of generalizability. The present study addressed these gaps by utilizing a large national dataset and stratifying the analysis by key sociodemographic characteristics. In Australia, previous studies have observed a declining incidence after 2010 but lacked comprehensive insights into how factors such as geographic location, socioeconomic status, and ethnic background influence these trends. Understanding these associations is crucial for developing targeted prevention and management strategies.

The Current Study

The present study utilized data from the National Diabetes Services Scheme (NDSS), a program that includes a registry of 80% to 90% of the individuals in Australia who have been diagnosed with diabetes. The researchers analyzed data from individuals aged 20 years or older registered between 2005 and 2019 in four jurisdictions: the Australian Capital Territory, Queensland, New South Wales, and Victoria, which account for approximately 80% of NDSS registrations.

To identify new cases of type 2 diabetes, the study defined incident cases as individuals registering for the first time. Additionally, diagnostic categorization was confirmed using clinical data and diagnostic codes. The researchers also used census-based indices such as the Australian Statistical Geography Standard and the Index of Relative Socioeconomic Disadvantage to classify geographic and socioeconomic data. Countries of birth were grouped into ten categories to explore ethnic disparities.

The study used various statistical analyses, including age-period-cohort modeling and Poisson regression, to account for changes over time and across demographic groups. The incidence rates were calculated annually and stratified by age, sex, country of birth, geographic remoteness, and socioeconomic disadvantage. These stratifications revealed variations in incidence trends within key subgroups.

Additional data on diagnostic test usage, such as hemoglobin A1c (HbA1c) and oral glucose tolerance tests, were also incorporated to understand diagnostic trends. The researchers sourced the population data from the Australian Bureau of Statistics to ensure accuracy in calculating risk estimates. This comprehensive approach also allowed them to explore both temporal and demographic variations in type 2 diabetes incidence and provide a nuanced view of trends and their underlying factors.

Major Findings

The researchers found that the overall incidence of type 2 diabetes in Australia had decreased from 2010 to 2019, following an earlier increase between 2005 and 2010. This decline was consistent across various demographic groups, including men, women, and individuals categorized by geographic remoteness and socioeconomic disadvantage. However, despite the general decline, the data highlighted persistent disparities, such as higher incidence rates among individuals in the most socioeconomically disadvantaged quintile and inner regional areas before 2015.

Notably, the incidence among people born in Australia or other English-speaking countries declined during the later years. However, an increasing trend was observed among individuals from North Africa, the Middle East, the Pacific Islands, and Asia after 2011. Furthermore, geographic trends were observed to shift over time, with inner regional areas initially having the highest incidence but major cities surpassing them after 2015.

Furthermore, men between the ages of 20 and 40 saw a slight increase in incidence from 2005 to 2019, which contrasted with declines in all other age groups and among women. This was attributed to both demographic shifts and potential changes in diabetes risk factors in this group. The study found that diagnostic practices had also evolved, with an increased reliance on HbA1c testing after 2012, while the use of oral glucose tolerance tests showed a decline. While these diagnostic changes partially explained some observed trends, the study emphasized that broader behavioral and environmental factors likely contributed significantly to the declining rates.

Conclusions

Overall, the study revealed a declining trend in type 2 diabetes incidence in Australia from 2010 to 2019, though increases were observed among individuals from specific ethnic backgrounds. While the findings highlighted the significant progress achieved in reducing diabetes incidence in the general population, they also highlighted the persistent disparities among specific demographic and ethnic groups. For example, incidence among men aged 20–40 years and individuals from Asia, North Africa, and the Middle East increased during the study period.

The study emphasized the importance of tailored prevention strategies in addressing these demographic and socioeconomic disparities. Understanding these trends is critical for designing equitable healthcare policies and interventions that mitigate the burden of diabetes across diverse populations. Furthermore, the study highlighted the importance of addressing gaps in data collection, such as missing country-of-birth information, to enhance future analyses.