Decreased Incidence of Type 1 Diabetes in Young Finnish Children
The incidence of type 1 diabetes has been rising for decades, particularly among young children. Between 2006 and 2011 the incidence rate reached a plateau in Finland. In this observational register-based cohort study, we assess recent trends in the disease rate in Finnish children.
RESEARCH DESIGN AND METHODS
Based on data from the Finnish Pediatric Diabetes Register, we studied the incidence of type 1 diabetes among children under the age of 15 years between 2003 and 2018. We assessed sex-specific incidence rates (IRs) per 100,000 person years (PY) by 4-year time periods in three age groups (0.50–4.99, 5.00–9.99, and 10.00–14.99 years).
Among the 7,871 children with newly diagnosed type 1 diabetes, the median age at diagnosis increased from 7.88 to 8.33 (P = 0.001), while the overall IR decreased from 57.9/100,000 PY in 2003–2006 to 52.2/100,000 PY in 2015–2018, yielding an IR ratio (IRR) of 0.90 (95% CI 0.85–0.96, P = 0.001). This decline was mainly due to the decrease in the youngest age group [IRR 0.77 (95% CI 0.68–0.87); P < 0.001], being significant both among males and females. In the middle age group, a significant decrease was observed only among females. No changes were observed in the oldest children.
The incidence of type 1 diabetes decreased among young Finnish children between 2003 and 2018. Current findings imply that environmental factors driving the immune system towards islet autoimmunity are changing in young children.