Infant exposures and development of type 1 diabetes mellitus: The Diabetes Autoimmunity Study in the Young (DAISY).

IMPORTANCE The incidence of type 1 diabetes mellitus (T1DM) is increasing worldwide, with the most rapid increase among children younger than 5 years of age. OBJECTIVE To examine the associations between perinatal and infant exposures, especially early infant diet, and the development of T1DM. DESIGN The Diabetes Autoimmunity Study in the Young (DAISY) is a longitudinal, observational study. SETTING Newborn screening for human leukocyte antigen (HLA) was done at St. Joseph's Hospital in Denver, Colorado. First-degree relatives of individuals with T1DM were recruited from the Denver metropolitan area. PARTICIPANTS A total of 1835 children at increased genetic risk for T1DM followed up from birth with complete prospective assessment of infant diet. Fifty-three children developed T1DM. EXPOSURES Early (<4 months of age) and late (≥6 months of age) first exposure to solid foods compared with first exposures at 4 to 5 months of age (referent). MAIN OUTCOME AND MEASURE Risk for T1DM diagnosed by a physician. RESULTS Both early and late first exposure to any solid food predicted development of T1DM (hazard ratio [HR], 1.91; 95% CI, 1.04-3.51, and HR, 3.02; 95% CI, 1.26-7.24, respectively), adjusting for the HLA-DR genotype, first-degree relative with T1DM, maternal education, and delivery type. Specifically, early exposure to fruit and late exposure to rice/oat predicted T1DM (HR, 2.23; 95% CI, 1.14-4.39, and HR, 2.88; 95% CI, 1.36-6.11, respectively), while breastfeeding at the time of introduction to wheat/barley conferred protection (HR, 0.47; 95% CI, 0.26-0.86). Complicated vaginal delivery was also a predictor of T1DM (HR, 1.93; 95% CI, 1.03-3.61). CONCLUSIONS AND RELEVANCE These results suggest the safest age to introduce solid foods in children at increased genetic risk for T1DM is between 4 and 5 months of age. Breastfeeding while introducing new foods may reduce T1DM risk.