Recurrent viral respiratory tract infections during first 6 months and risk of T1 diabetes

Using data for patients in Bavaria, Germany, the study included 295,420 infants, of whom 720 were diagnosed with T1D over a median follow-up of 8.5 years, for an incidence of 29 diagnoses per 100,000 children annually. At least 1 infection was reported during the first 2 years of life in 93 percent of all children, and in 97 percent of children with T1D.

Most children experienced respiratory and viral infections. The researchers found that T1D risk was increased in children who had a respiratory tract infection between birth and 2.9 months or between 3 and 5.9 months of age compared with children who had no respiratory tract infections in these age intervals. T1D risk was also increased among children who experienced a viral infection between birth and 5.9 months of age.

"It is unknown whether the association with early infections reflects increased exposure to virus or an impairment of the immune system response, perhaps due to genetic susceptibility," the authors write. "The association of respiratory tract infections in the first 6 months with T1D is consistent with smaller studies assessing autoantibody development, suggesting that the first half-year of life is crucial for the development of the immune system and autoimmunity."