Why children of mothers with type 1 diabetes get it less often: genes don't explain it, TEDDY study finds
In 6,942 children from the TEDDY cohort, those whose mothers had type 1 diabetes developed the disease at about half the rate of those whose fathers had it, despite similar genetic risk scores. The protective effect showed up in early childhood and faded after age 6.
It has long been observed that children whose mother has type 1 diabetes develop the disease less often than children whose father has it. A study led by the University of Colorado Anschutz and published in Diabetes Care (announced 10 November 2026) tested whether inherited genetic risk explains this.
What was studied
The team analysed 6,942 children in TEDDY (The Environmental Determinants of Diabetes in the Young), which follows children at increased genetic risk from infancy into adolescence, using an extended genetic risk score.
Findings
- Genetic risk scores did not differ significantly between children of affected mothers and of affected fathers.
- Yet children of affected mothers developed type 1 diabetes at about half the rate, and were less likely to develop islet autoimmunity, the early immune attack on insulin-producing cells.
- The lower risk of islet autoimmunity disappeared after age 6, and once autoimmunity began these children did not progress more slowly to diagnosis.
The authors say this challenges the idea that the effect is an artefact of the loss of the highest-risk pregnancies, and points to protective factors during pregnancy or early life; epigenetic changes are one mechanism they are investigating.
Limitations
- This is an observational cohort study; it does not identify the cause of the maternal protection.
- TEDDY includes only children at increased genetic risk, so results may not apply to all children.
- This summary is based on the university’s press release.
Families with type 1 diabetes questions should talk to their doctor.
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