Timing of initial cereal exposure in infancy and risk of islet autoimmunity

Context Dietary exposures in infancy have been implicated, albeit inconsistently, in the etiology of type 1 diabetes mellitus (DM). Objective To examine the association between cereal exposures in the infant diet and appearance of islet autoimmunity (IA). Design Birth cohort study conducted from 1994 to 2002 with a mean follow-up of 4 years. Setting Newborn screening for HLA was done at St Joseph's Hospital in Denver, Colo. First-degree relatives of type 1 DM individuals were recruited from the Denver metropolitan area. Participants We enrolled 1183 children at increased type 1 DM risk, defined as either HLA genotype or having a first-degree relative with type 1 DM, at birth and followed them prospectively. We obtained exposure and outcome measures for 76% of enrolled children. Participants had variable lengths of follow-up (9 months to 9 years). Main Outcome Measures Blood draws for the detection of insulin autoantibody, glutamic acid decarboxylase autoantibody, or IA-2 autoantibody were performed at 9, 15, and 24 months and annually thereafter. Children with A (n=34) were defined as those testing positive for at least 1 of the autoantibodies on 2 or more consecutive visits and who tested positive or had diabetes on their most recent visit. Results Children initially exposed to cereals between ages 0 and 3 months (hazard ratio [HR], 4.32; 95% confidence interval [CI], 2.0-9.35) and those who were exposed at 7 months or older (HR, 5.36; 95% Cl, 2.08-13.8) had increased hazard of A compared with those who were exposed during the fourth through sixth month, after adjustment for HLA genotype, family history of type 1 DM, ethnicity, and maternal age. In children who were positive for the HLA-DRB1*03/04,DQB8 genotype, adjusted HRs Were 5.55 (95% Cl, 1.92-16.03) and 12.53 (95% Cl, 3.19-49.23) for initial cereal exposure between ages 0 to 3 months and at 7 months or older, respectively. Conclusion There maybe a window of exposure to cereals in infancy outside which initial exposure increases A risk in susceptible children.