Risk of new-onset type 1 diabetes in individuals with celiac disease and thyroid disease—An observational study

Aims: The objective of this study was to compare the risk of developing type 1 diabetes in individuals with celiac disease, hyperthyroidism and hypothyroidism to that of individuals without those conditions. Materials and Methods: In this retrospective, observational, matched-cohort study based on real-world claims data, individuals with at least one diagnosis of celiac disease, hyperthyroidism (e.g. Graves' disease) or hypothyroidism (e.g. Hashimoto's disease) and a control cohort of individuals without any of these three conditions were included. Individuals from the disease and control cohorts were propensity score matched 1:1 based on baseline demographics and clinical characteristics. A Cox proportional hazards model was used to compare the risk of type 1 diabetes between cohorts. Results: Type 1 diabetes developed in 0.14% (68/47 099) of individuals with celiac disease compared to 0.06% (27/47 099) of controls. Of those with hyperthyroidism, type 1 diabetes developed in 0.17% (281/164 830) compared to 0.06% (99/164 830) of controls. Of those with hypothyroidism, type 1 diabetes developed in 0.18% (1756/980 477) compared to 0.08% (764/980 477) of controls. The risk of developing type 1 diabetes was increased for each of the disease cohorts compared to their respective controls (celiac disease: HR = 2.54 [p < 0.0001]; hyperthyroidism: adjusted HR = 2.98 [p < 0.0001]; hypothyroidism: HR = 2.41 [p < 0.0001]); risk was highest among individuals aged <18 years. Conclusions: The risk of developing type 1 diabetes was significantly higher for individuals with celiac disease or thyroid disease compared to those without any of these conditions. These findings support the screening of individuals with these conditions for stage 2 type 1 diabetes.