Microbial exposure in infancy and subsequent appearance of type 1 diabetes mellitus-associated autoantibodies: a cohort study

Suvi M Virtanen, Hanna-Mari Takkinen, Bright I Nwaru, Minna Kaila, Suvi Ahonen, Jaakko Nevalainen, Sari Niinistö, Heli Siljander, Olli Simell, Jorma Ilonen, Heikki Hyöty, Riitta Veijola, Mikael Knip

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)755-63
Number of pages9
JournalJAMA pediatrics
Issue number8
Publication statusPublished - Aug 2014


  • Animals
  • Anti-Infective Agents
  • Autoantibodies
  • Autoimmunity
  • Cats
  • Child, Preschool
  • Diabetes Mellitus, Type 1
  • Dogs
  • Environmental Exposure
  • Female
  • Finland
  • Genetic Predisposition to Disease
  • HLA Antigens
  • Humans
  • Hygiene
  • Infant
  • Infant, Newborn
  • Islets of Langerhans
  • Male
  • Microbiota
  • Questionnaires
  • Risk Factors


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