Abstract
BACKGROUND
Children and adolescents with type 1 diabetes mellitus (T1D) are at increased risk of developing additional autoimmune diseases. However, data on the frequency, spectrum, and timing of these comorbidities in long-term pediatric cohorts remain limited. This study aimed to evaluate the prevalence, clinical characteristics, and temporal relationships of autoimmune diseases in children and adolescents with T1D, as well as to identify factors associated with their occurrence.
METHODS
This retrospective study included 639 children and adolescents with T1D who were followed at a tertiary pediatric endocrinology center between January 2004 and October 2018. Demographic, clinical, laboratory, and autoantibody data were reviewed. Autoimmune diseases were identified through routine annual screening and clinical follow-up. Temporal relationships between T1D and autoimmune disease diagnoses were analyzed. Multivariable logistic regression was used to assess factors associated with additional autoimmune diseases.
RESULTS
At least one additional autoimmune disease was identified in 120 subjects with diabetes (18.8%). The most frequent comorbidities were autoimmune thyroiditis (AIT, 12.7%) and celiac disease (CD, 5.9%), followed by vitiligo (1.3%), autoimmune gastritis/pernicious anemia (0.15%), and autoimmune hepatitis (0.15%). Female sex was independently associated with the presence of additional autoimmune diseases (OR = 1.61, 95% CI 1.07-2.41, p  = 0.022). Most autoimmune diseases were diagnosed either concurrently with or after T1D onset, clustering within the first two years. A moderate positive correlation was observed between age at diagnosis of T1D and age at diagnosis of AIT ( r  = 0.586, p   p  < 0.001).
CONCLUSION
Autoimmune comorbidities, particularly AIT and CD, are common in pediatric T1D, with most diagnoses occurring within the first two years around diabetes onset. These findings support intensified and closer screening-especially during the early disease course and in female subjects with diabetes-to enable earlier detection and improved long-term management. This study provides valuable epidemiological data from Türkiye and contributes to global pediatric T1D literature.