Importance 
Dietary proteins, such as gluten, have been suggested as triggers of the disease process in type 1 diabetes (T1D).

Objective 
To study the associations of cereal, gluten, and dietary fiber intake with the development of islet autoimmunity (IA) and T1D.

Design, Setting, and Participants 
The prospective birth cohort Finnish Type 1 Diabetes
Prediction and Prevention Study recruited children with genetic
susceptibility to type 1 diabetes from September 1996 to September 2004
from 2 university hospitals in Finland and followed up every 3 to 12
months up to 6 years for diet, islet autoantibodies, and T1D. Altogether
6081 infants (78% of those invited) participated in the study. Dietary
data were available for 5714 children (94.0%) and dietary and IA data
were available for 5545 children (91.2%), of whom 3762(68%) had data on
islet autoantibodies up to age 6 years. Information on T1D was available
for all children. Data were analyzed in 2018 and end point data were
updated in 2015.

Exposures 
Each child’s intake of cereals, gluten, and dietary fiber was calculated from repeated 3-day food records up to 6 years.

Main Outcomes and Measures 
Islet autoimmunity was defined as repeated positivity for
islet cell antibodies and at least 1 biochemical autoantibody of 3
analyzed, or T1D. Data on the diagnosis of T1D were obtained from
Finnish Pediatric Diabetes Register.

Results 
Of 5545 children (2950 boys [53.2%]), 246 (4.4%) developed IA
and of 5714 children (3033 boys [53.1%]), 90 (1.6%) developed T1D during
the 6-year follow-up. Based on joint models, the intake of oats (hazard
ratio [HR], 1.08; 95% CI, 1.03-1.13), wheat (HR, 1.09; 95% CI,
1.03-1.15), rye (HR, 1.13; 95% CI, 1.03-1.23), gluten-containing cereals
(HR, 1.07; 95% CI, 1.03-1.11), gluten without avenin from oats (HR,
2.23; 95% CI, 1.40-3.57), gluten with avenin (HR, 2.06; 95% CI,
1.45-2.92), and dietary fiber (HR, 1.41; 95% CI, 1.10-1.81) was
associated with the risk of developing IA (HRs for 1 g/MJ increase in
intake). The intake of oats (HR, 1.10; 95% CI, 1.00-1.21) and rye (HR,
1.20; 95% CI, 1.03-1.41) was associated with the risk of developing T1D.
After multiple testing correction, the associations with IA remained
statistically significant.

Conclusions and Relevance 
A high intake of oats, gluten-containing cereals, gluten, and
dietary fiber was associated with an increased risk of IA. Further
studies are needed to confirm or rule out the findings and study
potential mechanisms.