Microbial Exposure in Infancy and Subsequent Appearance of Type 1 Diabetes Mellitus-Associated Autoantibodies: A Cohort Study

JAMA Pediatr. 2014 Aug;168(8):755-63. doi: 10.1001/jamapediatrics.2014.296.


Importance: The role of microbial exposure during early life in the development of type 1 diabetes mellitus is unclear.

Objective: To investigate whether animal contact and other microbial exposures during infancy are associated with the development of preclinical and clinical type 1 diabetes.

Design, setting, and participants: A birth cohort of children with HLA antigen-DQB1-conferred susceptibility to type 1 diabetes was examined. Participants included 3143 consecutively born children at 2 hospitals in Finland between 1996 and 2004.

Exposures: The following exposures during the first year of life were assessed: indoor and outdoor dogs and cats, farm animals, farming, visit to a stable, day care, and exposure to antibiotics during the first week of life.

Main outcomes and measures: Clinical and preclinical type 1 diabetes were used as outcomes. The latter was defined as repeated positivity for islet-cell antibodies plus for at least 1 of 3 other diabetes-associated autoantibodies analyzed and/or clinical type 1 diabetes. The autoantibodies were analyzed at 3- to 12-month intervals since the birth of the child.

Results: Children exposed to an indoor dog, compared with otherwise similar children without an indoor dog exposure, had a reduced odds of developing preclinical type 1 diabetes (adjusted odds ratio [OR], 0.47; 95% CI, 0.28-0.80; P = .005) and clinical type 1 diabetes (adjusted OR, 0.40; 95% CI, 0.14-1.14; P = .08). All of the other microbial exposures studied were not associated with preclinical or clinical diabetes: the odds ratios ranged from 0.74 to 1.58.

Conclusions and relevance: Among the 9 early microbial exposures studied, only the indoor dog exposure during the first year of life was inversely associated with the development of preclinical type 1 diabetes. This finding needs to be confirmed in other populations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Infective Agents / adverse effects
  • Autoantibodies / blood*
  • Autoimmunity*
  • Cats
  • Child, Preschool
  • Diabetes Mellitus, Type 1 / epidemiology
  • Diabetes Mellitus, Type 1 / genetics
  • Diabetes Mellitus, Type 1 / immunology*
  • Dogs
  • Environmental Exposure*
  • Female
  • Finland / epidemiology
  • Genetic Predisposition to Disease
  • HLA Antigens / genetics
  • Humans
  • Hygiene
  • Infant
  • Infant, Newborn
  • Islets of Langerhans / immunology
  • Male
  • Microbiota*
  • Risk Factors
  • Surveys and Questionnaires


  • Anti-Infective Agents
  • Autoantibodies
  • HLA Antigens