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Risk of allergic conjunctivitis in patients with type 1 diabetes mellitus: a population-based retrospective cohort study
  1. Yin-Huei Chen1,
  2. Cheng-Li Lin2,3,
  3. Da-Tian Bau4,
  4. Yi-Chih Hung1,5
  1. 1 Division of Endocrinology and Metabolism, Department of Medicine, China Medical University Hospital, Taichung, Taiwan
  2. 2 Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan
  3. 3 College of Medicine, China Medical University, Taichung, Taiwan
  4. 4 Terry Fox Cancer Research Laboratory, China Medical University Hospital, Taichung, Taiwan
  5. 5 Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
  1. Correspondence to Dr Yi-Chih Hung; viennaspring0312{at}


Objective In accordance with the dichotomy between T helper type 1(Th1) and T helper type 2 (Th2) responses, the occurrence of allergic conjunctivitis (AC) and type 1 diabetes mellitus (T1DM) is, in theory, inversely related in the individual. However, recent studies investigating the association between the two diseases are controversial.

Design Population-based cohort study.

Setting We used claims data of the National Health Insurance Research Database of Taiwan.

Participants We identified 4160 patients aged 1–30 years with newly diagnosed T1DM and no history of AC at baseline. For each patient with T1DM, four non-T1DM controls (n=16,640) were matched by sex. The mean follow-up time was 6 years.

Primary and secondary outcome measures Multivariate Cox proportional hazards regression analysis was used to evaluate the risk of AC. We additionally evaluated the association between risk of AC and T1DM progression by examining Diabetes Complications Severity Index (aDCSI) changes from the date of diagnosis until the end of follow-up.

Results The overall incidence of allergic conjunctivitis (AC) was higher in the type 1 diabetes mellitus (T1DM) cohort than in the control cohort (23.0 vs 13.5 per 1000 person-years, adjusted incidence rate ratio (aIRR): 1.59, 95% CI 1.47 to 1.71). Relative to that in patients with mildly progressive T1DM, the risk of AC increased as the adapted Diabetes Complications Severity Index (aDCSI) increased (aIRR: 1.68, 3.78 and 18.8, with yearly changes in aDCSI score: 0.51 to 1.00, 1.01 to 2.00, and >2.00 vs <0.51, respectively; for trend <0.001).

Conclusion Patients with T1DM are at an elevated risk of developing AC; this risk increases with T1DM progression. The T helper type 1/T helper type 2 hypothesis is an overly simplistic explanation for this association.

  • allergic conjunctivitis
  • type 1 diabetes mellitus
  • atopy
  • B lymphocytes
  • T cells

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  • Contributors YHC: wrote the manuscript.

    CLL: data analysis and interpretation.

    DTB: critical discussion.

    YCH: study design, wrote the manuscript, data interpretation, revised and approved the manuscript.

  • Competing interests None declared.

  • Patient consent This study was found to fulfil the conditions for exemption by the Institutional Review Board (IRB) of China Medical University (CMUH-104-REC2-115). The IRB also specifically waived the consent requirement.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement There were no additional unpublished data from this study.