TEDDY Study Nears Completion in Type 1 Diabetes Research

Sweden and Finland are the two top countries for incidence rates of type 1 diabetes in children in the world. Today, more than 1.2 million children and adolescents under the age of 20 have type 1 diabetes. The incidence of the disease is also increasing worldwide. People with type 1 diabetes require treatment with insulin to survive and it is important to understand the causes of type 1 diabetes to prevent or delay the disease progression.

The TEDDY study began in 2004 and includes almost 8,700 children from Sweden, Finland, Germany and the United States. The research project is funded by the U.S. National Institutes of Health (NIH) and aims to ascertain what causes children to develop type 1 diabetes.

The study, which has led to the publication of many peer-reviewed studies in high impact journals, provides additional evidence for the theory that a combination of genetic and environmental factors affects whether a person develops the disease.
The most important lessons from the study are presented in Nature Reviews Endocrinology, ahead of the final collection of data and samples in March 2025. Åke Lernmark, principal investigator of the TEDDY study in Sweden, has led work on the article. Jeffrey Krischer, director of the TEDDY Data Coordinating Center and co-chair of the international TEDDY study, is one of the leading co-authors.

"The study's success is due to the commitment and sacrifice on the part of the participating children and their families. Most were reassured by the close relationships with study coordinators and the careful monitoring of diabetes risk provided by the study. Many of the participating families wanted to help us understand the causes of the disease," says Jeffrey Krischer, professor and director of the Health Informatics Institute at the University of South Florida.

Screening for type 1 diabetes

In the study, the researchers have followed the development of diabetes-related autoantibodies in children. A blood sample showing the presence of one of four diabetes-related autoantibodies suggests that cells in the pancreas that produce insulin are attacked by the body's own immune system. The TEDDY study has shown, among other things, that autoantibodies formed against insulin are most common during the child's first three years. The discovery of genetic risk factors has enabled the researchers to estimate an individual's risk of developing the disease.

"Some of us believed that the disease would be diagnosed shortly after the first autoantibody against insulin was formed, but our studies have shown that it can take several years before the child develops the disease. Interest in screening for type 1 diabetes within the healthcare system is increasing in many countries, and our genetic risk scores can be used to identify which children may benefit most from being screened for the disease," says Åke Lernmark, senior professor of experimental diabetes at Lund University Diabetes Centre and a member of the study's steering committee.

Continued research

The researchers have also found a connection between enterovirus infection, the development of diabetes-related autoantibodies and type 1 diabetes. Another important finding is that administering probiotics to infants at increased risk of developing the disease can reduce the risk of them developing diabetes-related autoantibodies.

Results from the TEDDY study have contributed to the development of several new research projects that are currently underway at Lund University Diabetes Centre. Research within the POInT study, for example, has shown that young children with a genetic risk of developing type 1 diabetes had an increased risk of developing diabetes-related autoantibodies in connection with Covid-19 infection. The AVAnT1A study examines whether vaccination against Covid-19 can prevent the development of these autoantibodies. In the SINT1A study, researchers investigate whether probiotics can prevent type 1 diabetes in children with increased risk.

The TEDDY study has also increased knowledge about celiac disease and thyroiditis, two other autoimmune diseases. The participants have been screened for autoantibodies associated with the two diseases. This knowledge is being used in the TRIAD study, which screens children in southern Sweden for the three diseases: type 1 diabetes, celiac disease and thyroiditis. The goal of TRIAD is to investigate different methods that can be used for screening autoimmune diseases within the healthcare system.

"It is incredible to see that results from the TEDDY study have led to new studies. Even if we stop collecting samples from the children, analysis of the data continues. An important question that remains to be answered is what role viral infections play in the development of the disease. If we get a firm answer to this question, we can find new ways to stop the disease," says Åke Lernmark.