Clustering patterns in Finnish type 1 diabetes patients: a nationwide register-based study
Authors' conclusion
These results demonstrate evidence of spatiotemporal clustering of T1DM in Finnish children, supporting the hypothesis of environmental triggers in T1DM etiology. These findings highlight the need for further research to identify the specific environmental factors and mechanisms behind the clustering.
Study context
- Population
- Finnish children under 18 diagnosed with T1D between 1990 and 2019 (Finnish Social Insurance Institution); median age at diagnosis 8.9 years; 56% male
- Participants
- 16,307 vs 48,914
- Comparison
- T1D cases vs matched controls
- Casesn = 16,307
- Controlsn = 48,914reference
- Outcome
- Spatial and spatiotemporal clustering of T1D (Cuzick-Edwards test, Knox test, Jacquez's Q statistic)
Methodological detailsage- and sex-matched controls (3 per case), Benjamini-Hochberg correction for multiple testing
- Age- and sex-matched controls (3 per case)
- Benjamini-Hochberg correction for multiple testing
Main finding
As reported in the abstract
- Cuzick-Edwards test: modest spatial clustering among males 1 year prior to diagnosis
- Knox test: significant spatiotemporal clustering across all cases
- Analyses with full residential histories confirmed these findings
Observational data: associations, not effects.
Further findings
- More pronounced spatiotemporal clustering in children over 6 years old
Original publication
Clustering patterns in Finnish type 1 diabetes patients: a nationwide register-based study. BMJ Open Diabetes Res Care. Published 30 December 2025. doi:10.
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