Parents' autoimmune diseases may lead to higher risk of type 1 diabetes in their children

Children whose mothers had an autoimmune disease before or during pregnancy had a 57% higher risk of developing type 1 diabetes (T1D) than children whose mothers did not, according to a Swedish study of nearly 1.46 million children published Oct. 26, 2026, in JAMA Pediatrics.

T1D is among the most common autoimmune diseases in children and teens. It develops as the immune system destroys the insulin-producing cells of the pancreas, leaving people dependent on insulin for life. The study authors noted that T1D incidence has risen steadily worldwide over recent decades. Having a parent with T1D is a well-established risk factor. Much less is known about whether a parent's other autoimmune conditions, such as rheumatoid arthritis or celiac disease, also raise a child's risk.

The FDA approved Tzield (teplizumab) in November 2022 to delay the onset of stage 3 T1D in people 8 years and older with stage 2 disease. In April 2026, the FDA expanded that indication to children as young as 1 year, according to drugmaker Sanofi. In June 2026, the drug also received accelerated approval to delay the decline in the body's own insulin production in children ages 8 to 17 recently diagnosed with stage 3 T1D, the company said.

Huan Zhang, Ph.D., a professor in the Department of Global Public Health at Karolinska Institutet in Stockholm and Suzhou Medical College of Soochow University in China, led the study. Zhang and his team set out to look at a broad range of maternal autoimmune diseases and compare mothers directly with fathers, which few large studies have done. Comparing parents can help separate risk tied to pregnancy itself from risk that runs in families.

Researchers followed 1.46 million children for about 15 years

The team used linked national health registers to follow all live-born single children born in Sweden from January 2001 through December 2014. Each child was tracked from birth until a T1D diagnosis, death, emigration or the end of 2023. Median follow-up was 15.3 years.

Researchers looked at autoimmune diseases diagnosed in either parent before or during the pregnancy. The main analysis adjusted for factors such as birth year, education, diabetes and the other parent's autoimmune disease. A second analysis also adjusted for parental T1D to see whether other autoimmune conditions carried risk on their own. The team then compared mothers with fathers directly. In addition, a cousin comparison of 821,824 children looked at differences within extended families to account for shared genetics and environment.

Risk was similar whether mom or dad had the disease

Out of the 10,273 children (0.71%) who developed T1D, 88,368 (6.1%) were exposed to a maternal autoimmune disease. In the main analysis, maternal autoimmune disease was linked to a 57% higher risk of T1D. Exposed children were diagnosed at a rate of 8.19 cases per 10,000 person-years, compared with 4.39 among children who were not exposed. Maternal T1D alone was tied to a risk about 4.5 times higher.

When researchers looked only at autoimmune diseases other than T1D and also adjusted for maternal T1D, the link was smaller but held, at a 32% higher risk. Paternal autoimmune disease showed a similar pattern, with a 51% higher risk in the main analysis and 21% in the analysis that also adjusted for paternal T1D.

When the researchers compared mothers and fathers directly, they found no overall difference. In the cousin comparison, the link with maternal autoimmune disease weakened but persisted, at a 27% higher risk.

Results did vary by condition. For example, rheumatoid arthritis was tied to higher risk whether the mother or father had it. Autoimmune thyroiditis was linked to higher risk in both parents, though the association was stronger for fathers.

Celiac disease, vitiligo and ankylosing spondylitis in mothers, and sarcoidosis in fathers, were also tied to higher risk. For parental T1D, risk was highest when both parents had it, followed by father only and then mother only.

Maternal autoimmune diseases diagnosed before pregnancy showed stronger links than those first diagnosed after delivery, and preterm birth or abnormal fetal growth did not explain the association. Links were generally strongest for T1D that began in early childhood.

The authors said the similar results for mothers and fathers point to a shared family susceptibility, while differences across specific diseases suggest some conditions may also involve parent-specific or pregnancy-related influences.

“Together, these findings support a multifactorial model of intergenerational autoimmune transmission,” they wrote.

Genetic data and disease severity were not available

The study drew on nationwide data with nearly complete follow-up, and its size allowed researchers to examine a wide range of conditions in both parents. Because it was observational, it shows an association, not that a parent's disease causes T1D.

Some diagnoses may have been misclassified, especially milder conditions managed outside specialist care, though the authors said this would more likely weaken the findings than inflate them. Without genetic data, the researchers could not fully separate inherited risk from effects during pregnancy.

Data on disease severity, autoantibody levels and treatment were also unavailable. The cousin comparison could not account for household factors such as family size or shared childhood infections, and some less common conditions had too few cases for precise estimates.

The authors cautioned that the disease-specific findings are exploratory and based on relatively few exposed cases.

“Further studies are needed to investigate whether our results may be replicated in independent samples,” they said.