Long‐term coeliac disease influences risk of death in patients with type 1 diabetes

Aim The aim of this study was to examine mortality in patients with both type 1 diabetes ( T 1 D ) and coeliac disease ( CD ). Methods Between 1969 and 2008, we identified individuals with CD through biopsy reports from all pathology departments ( n  =   28) in S weden. T 1 D was defined as a diagnosis of diabetes recorded in the S wedish N ational P atient R egister between 1964 and 2009 in individuals aged ≤30 years. During follow‐up, we identified 960 patients with both T 1 D and CD . For each individual with T 1 D and CD , we selected up to five subjects with T 1 D alone (i.e. no CD ), matched for sex, age and calendar period of diagnosis, as the reference group ( n  =   4608). Using a stratified C ox regression analysis with CD as a time‐dependent covariate, we estimated the risk of death in patients with both T 1 D and CD compared with those with T 1 D alone. Results Stratifying for time since CD diagnosis, CD was not a risk factor for death in patients with T 1 D during the first 5 years after CD diagnosis [hazard ratio ( HR ) 0.87, 95% confidence interval ( CI ) 0.43–1.73], but thereafter the HR for mortality increased as a function of follow‐up time (5 to <10 years, HR 1.44, 95% CI 0.74–2.79; 10 to <15 years, HR 1.88, 95% CI 0.81–4.36). Having a CD diagnosis for ≥15 years was associated with a 2.80‐fold increased risk of death in individuals with T 1 D (95% CI 1.28–6.12). Conclusion A diagnosis of CD for ≥15 years increases the risk of death in patients with T 1 D .