Type 1 diabetes and microscopic colitis: A nationwide matched case–control study in Sweden.

Summary: Background and Aims: Microscopic colitis (MC) is a colonic inflammatory condition associated with autoimmune dysfunction. Type 1 diabetes (T1D) is a chronic disease induced by autoimmune destruction of pancreatic β‐cells. We aimed to examine the association between T1D and MC. Methods: A matched case–control study was conducted using the nationwide ESPRESSO cohort as study base. All biopsy‐confirmed MC patients born after 1940 were identified and compared to biopsy‐free individuals matched from the general population for T1D diagnosis using the Swedish National Patient Register. The T1D‐MC association was estimated as odds ratios (ORs) and 95% confidence intervals (CIs) by conditional logistic models, considering differences by sex and MC subtype. Full sibling comparison and adjustment for MC‐associated medications were also performed. Results: We identified 352 (3.7%) and 945 (2.0%) T1D diagnoses from 9,600 MC cases and 47,870 matched population controls, respectively, which corresponded to an overall OR of 1.79 (95% CI: 1.56–2.05). The association was stronger for collagenous colitis (OR, 2.15; 95% CI: 1.70–2.71) than lymphocytic colitis (OR, 1.62; 95% CI: 1.37–1.92) and remained statistically significant in full sibling comparison (OR, 1.46; 95%: 1.18–1.81). Medication adjustment attenuated the association to null among females (OR: 1.02; 95% CI: 0.82–1.27) but not among males (OR: 1.45; 95% CI: 1.11–1.90). Conclusion: T1D diagnosis was almost 80% more prevalent in MC patients compared to general population. This positive association did not seem to be spurious due to residual confounding shared by full siblings but may relate to consumption of medications associated with MC onset. [ABSTRACT FROM AUTHOR]