Childhood-onset type 1 diabetes in Western Australia: An update on incidence and temporal trends from 2001 to 2022

Objective: To determine the incidence and incidence trends over 2001–2022 of childhood-onset type 1 diabetes (T1D) in Western Australia and assess the impact of the COVID-19 pandemic. 

Methods: Children newly diagnosed with T1D aged 0–14 years in Western Australia from 1 January 2001 to 31 December 2022 were identified from the population-based Western Australian Children's Diabetes Database. Annual age- and sex-specific incidence was calculated, and Poisson regression was used to analyse trends by calendar year, month, sex and age group at diagnosis. Pandemic era impacts were also examined using the regression model adjusted for sex and age group. 

Results: Between 2001 and 2022, 2311 children (1214 boys, 1097 girls) were newly diagnosed with T1D aged 0–14 years, giving an overall mean annual incidence of 22.9 per 100,000 person-years (95% CI: 22.0, 23.9), with no significant difference observed between boys and girls. A significant linear increasing trend was only observed in 10–14 year olds with boys and girls combined (1.2% per year [IRR 1.012 (95% CI: 1.002, 1.022)]). No significant difference in the incidence was observed between the pre- and post-pandemic period. 

Conclusions: The incidence of type 1 diabetes in 0–14 year old Western Australian children continues to increase in the oldest age group. Longer term monitoring of the incidence during the COVID-19 pandemic is needed to determine its impact on this globally unique population which experienced a delayed start to the pandemic with severe containment measures remaining in place until January 2022.