Objective: Celiac disease (CD) is associated with type 1 diabetes (T1D). In the current study, we examined whether CD affects the risk of diabetic retinopathy (DRP) in patients with T1D.
Research design and methods: This was a population-based cohort study. Through the Swedish National Patient Register, we identified 41,566 patients diagnosed with diabetes in 1964-2009 and who were ≤30 years of age at diagnosis. CD was defined as having villous atrophy (Marsh stage 3) according to small intestinal biopsies performed between 1969 and 2008, with biopsy reports obtained from Sweden's 28 pathology departments. During follow-up, 947 T1D patients had a diagnosis of CD. We used Cox regression analysis with CD as a time-dependent covariate to estimate adjusted hazard ratios (aHRs) for DRP in patients with T1D and CD and compared them with patients with T1D but no CD.
Results: Duration of CD correlated with the risk of DRP. When results were stratified by time since CD diagnosis, individuals with T1D and CD were at a lower risk of DRP in the first 5 years after CD diagnosis (aHR 0.57 [95% CI 0.36-0.91]), followed by a neutral risk in years 5 to <10 (1.03 [0.68-1.57]). With longer follow-up, coexisting CD was a risk factor for DRP (10 to <15 years of follow-up, aHR 2.83 [95% CI 1.95-4.11]; ≥15 years of follow-up, 3.01 [1.43-6.32]).
Conclusions: Having a diagnosis of CD for >10 years is a risk factor for the development of DRP in T1D. Long-standing CD in patients with T1D merits intense monitoring of DRP.