Gut microbiome maturation in early childhood interacts with host genetics to predict type 1 diabetes risk.

Prospective evidence linking early-life microbiome development and host genetics with type 1 diabetes (T1D) risk is limited. Here, we describe how gut microbiome maturation and host genetics influence T1D risk in the TEDDY study. We analysed 12,151 longitudinal metagenomes and host genetic data from 887 children at high genetic risk for T1D followed for up to 6 years. We identify three microbiome maturational patterns: Early Matured, Late Matured and Early Plateaued, driven primarily by non-linear changes in species from the Bifidobacterium and Ruminococcus genera. The Early Matured pattern is enriched in galactose metabolism and exhibits higher production of aromatic amino acids and B-group vitamins at early follow-ups, whereas the Early Plateaued pattern has increased microbial production of branched-chain amino acids. Notably, the Early Plateaued pattern is associated with a threefold elevated risk of T1D, whereas other patterns are not associated with T1D risk. Furthermore, we find that host genetic variants related to antimicrobial and antiviral immune responses modify the association between the Late Matured pattern and T1D risk. These findings highlight the role of early microbial exposures and host genetics in T1D susceptibility.