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Research Christmas 2020: The Citadel

The shared risk of diabetes between dog and cat owners and their pets: register based cohort study

BMJ 2020; 371 doi: https://doi.org/10.1136/bmj.m4337 (Published 10 December 2020) Cite this as: BMJ 2020;371:m4337
  1. Rachel Ann Delicano, research assistant1,
  2. Ulf Hammar, senior statistician1,
  3. Agneta Egenvall, professor2,
  4. Carri Westgarth, senior lecturer3,
  5. Mwenya Mubanga, postdoctoral researcher4,
  6. Liisa Byberg, associate professor5,
  7. Tove Fall, professor1,
  8. Beatrice Kennedy, postdoctoral researcher1
  1. 1Department of Medical Sciences, Molecular Epidemiology and Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden
  2. 2Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
  3. 3Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
  4. 4Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  5. 5Department of Surgical Sciences, Orthopaedics, Uppsala University, Uppsala, Sweden
  1. Correspondence to: B Kennedy beatrice.kennedy{at}medsci.uu.se
  • Accepted 6 November 2020

Abstract

Objective To investigate whether dog and cat owners and their pets share a risk of developing diabetes.

Design Cohort study.

Setting Register based longitudinal study, Sweden.

Participants 208 980 owner-dog pairs and 123 566 owner-cat pairs identified during a baseline assessment period (1 January 2004 to 31 December 2006).

Main outcome measures Type 2 diabetes events in dog and cat owners and diabetes events in their pets, including date of diagnosis during the follow-up period (1 January 2007 to 31 December 2012). Owners with type 2 diabetes were identified by combining information from the National Patient Register, the Cause of Death Register, and the Swedish Prescribed Drug Register. Information on diabetes in the pets was extracted from veterinary care insurance data. Multi-state models were used to assess the hazard ratios with 95% confidence intervals and to adjust for possible shared risk factors, including personal and socioeconomic circumstances.

Results The incidence of type 2 diabetes during follow-up was 7.7 cases per 1000 person years at risk in dog owners and 7.9 cases per 1000 person years at risk in cat owners. The incidence of diabetes in the pets was 1.3 cases per 1000 dog years at risk and 2.2 cases per 1000 cat years at risk. The crude hazard ratio for type 2 diabetes in owners of a dog with diabetes compared with owners of a dog without diabetes was 1.38 (95% confidence interval 1.10 to 1.74), with a multivariable adjusted hazard ratio of 1.32 (1.04 to 1.68). Having an owner with type 2 diabetes was associated with an increased hazard of diabetes in the dog (crude hazard ratio 1.28, 1.01 to 1.63), which was attenuated after adjusting for owner’s age, with the confidence interval crossing the null (1.11, 0.87 to 1.42). No association was found between type 2 diabetes in cat owners and diabetes in their cats (crude hazard ratio 0.99, 0.74 to 1.34, and 1.00, 0.78 to 1.28, respectively).

Conclusions Data indicated that owners of a dog with diabetes were more likely to develop type 2 diabetes during follow-up than owners of a dog without diabetes. It is possible that dogs with diabetes could serve as a sentinel for shared diabetogenic health behaviours and environmental exposures.

Footnotes

  • Contributors: TF, UH, BK, and RAD designed the study. TF acquired the data, MM cleaned the data, and UH ran the statistical analyses. RAD conducted the literature review and wrote the first draft of the manuscript. TF, UH, BK, MM, RAD, AE, CW, and LB interpreted the results and critically revised the manuscript. TF and BK are the study supervisors and share senior authorship. TF and BK had full access to all the data in the study and are the guarantors. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: This project received financial support from the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS, 2013-1673), the Agria and the Swedish Kennel Club Research Foundation, and the Göran Gustafsson Foundation, all through grants to TF. TF is also a holder of a European Research Council starting grant (No 801965). The funders had no role in considering the study design or in the collection, analysis, interpretation of data, writing of the report, or decision to submit the article for publication.

  • Competing interests: All authors have completed the ICMJE uniform disclosure format at www.icmje.org/coi_disclosure.pdf and declare: support from Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, the Agria and the Swedish Kennel Club Research Foundation, and the Göran Gustafsson Foundation; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the Swedish Ethical Review Authority, Stockholm, Sweden (DNR 2012/1114-31/2, with amendments 2013-1687-32 and 2016/1392-31/1). All analyses were performed on pseudonymised data.

  • Data sharing: The register data in this study originate from Statistics Sweden, the National Board of Health and Welfare, and Agria Pet Insurance. Restrictions apply to the availability of these data, which were used under license and ethical approval and are not publicly available. Data are, however, available from the authors upon reasonable request and with written permission from the Swedish Ethical Review Authority.

  • The lead authors (the manuscript’s guarantors TF and BK) affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

  • Dissemination to participants and related patient and public communities: The study population was generated by register linkages between information from Agria Pet Insurance and official Swedish registers. Only pseudonymised data were delivered to the researchers. Direct dissemination of study results to study participants is therefore not possible. No patient organisation is invested in shared diabetes risk of pet owners and their pets.

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

http://creativecommons.org/licenses/by/4.0/

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/.

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