Several studies have examined duration of breastfeeding and introduction of solid foods in the development of type 1 diabetes (T1D) related islet autoimmunity (IA). This is the first attempt to study the association in a multi-country setting.
The Environmental Determinants of Diabetes in the Young (TEDDY) study prospectively follows 8502 children with T1D-associated HLA-DR-DQ alleles in Finland, Germany, Sweden and the US. Blood samples were collected every 3 months from birth to evaluate the primary outcome of IA, defined as appearance of one or more of the islet cell autoantibodies GADA, IAA, or IA-2A confirmed at two consecutive visits. The introduction time of solid foods was classified: less than 4 months, 4-5.9 months and 6 months or later. Children followed at least 1 year (n=7471) were included in the study. We applied time-to-event analysis adjusting for country, family T1D status, HLA type, gender, delivery type, birth order, marital status of the mother and maternal smoking during pregnancy.
Breastfeeding duration was not associated with IA. Significant interactions between the HLA-DR-DQ genotype and some diet variables were detected. Introduction of any solid food before 4 mo was associated with increased IA risk (HR 1.73; 95%CI 1.04-2.88) when compared to introduction at ≥6 mo, in HLA-DR3/4 carriers but not in non-HLA-DR3/4 carriers. Introduction of any solid food at 4-6 mo vs at ≥6mo was not associated with IA (HR 1.54; 95%CI 0.93-2.52) in HLA-DR3/4 carriers. In non-DR3/4 carriers, introduction of fruits/berries before 4 mo was associated with decreased IA risk compared to introduction at ≥6 mo (HR 0.55; 95%CI 0.35-0.86) but introduction of fruits/berries at 4-6mo vs at ≥6mo was not associated with IA (HR 0.87; 95%CI 0.63-1.19) in non-DR3/4 carriers.
We conclude that timing of solid food introduction may be associated with IA in TEDDY in a manner linked to HLA risk.