A new study:
What the study asked: Can how a child’s gut microbiome develops in early life help predict type 1 diabetes in children already at high genetic risk? Type 1 diabetes affects more than 9 million people worldwide, including 1.8 million children and adolescents.
Who did it and how: A prospective study led by Mass General Brigham, the Broad Institute of MIT and Harvard, and Harvard T.H. Chan School of Public Health, published in Nature Metabolism. It analyzed the TEDDY Study — 887 children at high genetic risk for type 1 diabetes from Finland, Germany, Sweden and the U.S., with more than 12,000 stool samples collected over their first 6 years of life.
The researchers counted a child as developing the disease process when blood tests first detected an immune attack on insulin-producing cells, or when they were clinically diagnosed.
Three microbiome patterns were found:
- Early-matured: rapid change in the first year, high bacterial diversity.
- Late-matured: slow start with low diversity around age 1, but caught up later.
- Early-plateaued: slow start that never caught up — low diversity through the first 3 years.
Children with the early-plateaued pattern had about 3 times the risk of developing type 1 diabetes or the early immune attack, compared to children whose microbiomes matured on a typical schedule. This was only visible through repeated sampling over time, not a single snapshot.
Biology behind it: The early-matured group shifted sooner from milk-adapted bacteria like Bifidobacterium to species that break down dietary fiber. The early-plateaued group stayed oriented toward digesting milk sugars even after solids were introduced, and relied on a narrower set of species for key functions.
Genetics mattered too: Lead author Danyue Dong, PhD, and co-corresponding author Daniel Wang, MD, ScD, found that genetic background influenced the link. Variants involved in antimicrobial and antiviral immune responses shaped how strongly the late-matured pattern related to risk. The early-plateaued pattern carried higher risk regardless of genetic background. Combining microbiome and genetic data gave a more accurate risk picture.
Limitations and next steps: This was an observational study in high-risk children, so it cannot prove cause and effect and may not apply to the general population. The authors suggest future pediatric visits could include gut microbiome testing in the first years of life, opening a window for microbiome-directed prevention strategies like dietary supplements — but clinical trials are needed first.