Incidence of type 1 diabetes in 0 to 14 year olds in Australia from 2002 to 2017

Objective To determine the incidence of childhood onset type 1 diabetes in Australia from 2002 to 2017, and analyze incidence rate trends by calendar year, sex, and age at diagnosis. Research Design and Methods Children newly diagnosed with type 1 diabetes aged <15 years between 2002 and 2017 were identified from the National Diabetes Register, estimated to be 99% complete. Data were obtained for diagnosis year, sex, age, and residential State/Territory at time of diagnosis. Population estimates by year, sex, single year of age, and State/Territory were obtained from the Australian Bureau of Statistics and Poisson regression used to examine incidence and trends by calendar year, sex, and age group at diagnosis. Results Between 2002 and 2017, there were 16 783 newly diagnosed cases of type 1 diabetes in children aged < 15 years (8684 boys: 8099 girls), giving a mean incidence of 25.0/1 00 000 person years (95%CI: 24.6, 25.4). A sinusoidal pattern in the incidence rate trend was observed with 5-yearly cycles providing the best model fit. No significant difference was observed in boys compared to girls (IRR 0.98 [95%CI: 0.95, 1.01]). Compared to 0 to 4 year olds, the mean incidence was 75% higher in 5 to 9 year olds, and 224% higher in 10 to 14 year olds. A decreasing incidence rate trend was observed in 0 to 4 year old boys and girls. Conclusions This study reports updated incidence and incidence rate trends in children and adolescents diagnosed with type 1 diabetes in Australia. A cyclical pattern in incidence trend persists, with an overall decreasing trend observed only in the youngest age group.