OBJECTIVE The association between autoimmune diseases and type 1 diabetes (T1D) is mostly based on studies among people with T1D at baseline. We assessed the risk of incident T1D among adolescents with other autoimmune diseases. RESEARCH DESIGN AND METHODS Included were all Israeli adolescents without a history of dysglycemia, aged 16–19 years, undergoing medical evaluation before mandatory military service between January 1996 and December 2016. Data were linked with information on adult-onset T1D from the Israeli National Diabetes Registry. The cohort was dichotomized by the presence of any autoimmune disease. Cox proportional hazards modeling was applied. RESULTS A total of 1,426,362 people were included, of whom 38,766 (2.7%) had a history of autoimmunity at study entry (10,333 with autoimmune thyroid disease AITD and 9,603 with celiac disease). Over 15,810,751 person-years of follow-up, there were 37 and 740 incident cases of T1D among people with and without autoimmunity, respectively, and a crude incident rate of 9.6 and 4.8 case/105 person-years, respectively. In a multivariable model adjusted for sex, birth year, and sociodemographic variables the hazard ratio (HR) for incident T1D among people with autoimmunity was 2.19 (95% CI 1.57–3.04) versus those without. Results persisted when islet-autoantibody data were used as mandatory criteria for T1D case definition (HR 2.22, 95% CI 1.13–4.35). The HRs among people with AITD and celiac disease were 3.99 (2.5–6.4) and 2.82 (1.46–5.45), respectively. CONCLUSIONS Autoimmune diseases in late adolescence were associated with an increased risk of T1D in adulthood in both sexes, especially among those with AITD and celiac disease.
Twig et al. (2025) studied this question.