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Keywords:

  • case-crossover;
  • hygiene hypothesis;
  • infections;
  • type 1 diabetes;
  • viral

Abstract

Background

Infectious diseases have been associated with increased risk of type 1 diabetes (T1D). The objective of this case-crossover was to quantify the role of infectious diseases as triggers for T1D, 1 and 2 yr preceding disease diagnosis.

Methods

All children aged 2–18 yr diagnosed with T1D between 2004 and 2009 among a two million member Israeli healthcare organization were identified (n = 368). For each patient, visits to physicians with symptomatic infectious diseases during 1 and 2 yr before T1D diagnosis were collected and compared. A similar analysis was conducted in a population of non-diabetic members matched on exact date of birth, sex and socioeconomic status (n = 307).

Results

The rate of systemic viral infections was significantly higher in the year before T1D onset, as compared to the prior year [27 vs. 7%, respectively, odds ratio (OR) = 4.7, 95% confidence intervals (CI): 2.9–8.2]. This difference was most significant among patients diagnosed with T1D at the age of 2 to 6 (5 vs. 46%, respectively, OR = 27.0, 95% CI: 4.5–1105.4). Among non-T1D patients of the same age group, no difference was found in the proportion of patients with viral diseases 1 and 2 yr prior to T1D diagnosis (44 vs. 49%, respectively, OR = 0.8, 95% CI: 0.4–1.6). This unique association was limited only to viral diseases and to patients diagnosed with T1D at young age.

Conclusions

Our results indicate that T1D occurring in toddlers is characterized with a relatively low incidence of viral disease 2 yr prior to diagnosis and a much higher incidence in the subsequent year.