Lund University, Medical Faculty

Moving to Sweden increases the risk of diabetes

Ahmed Delli

Published 2010-03-25

Children of immigrants from countries with low risk of type 1 diabetes develop the disease more often than expected if they grow up in Sweden, which is a high-risk country. Scientists mean that it is something in the Swedish environment that causes this elevated risk.

Ahmed Delli, who is a scientist at Lund University Diabetes Centre, has mapped what happens when a child moves from an area with low risk of type 1 diabetes to an area with high risk, such as Sweden. "The risk more than doubles for children with parents from North Africa and the Middle East, for example", says Ahmed Delli, who is publishing the results of his study in Pediatric Diabetes.

Countries with high vs. low risk
When it comes to how many children develop type 1 diabetes in different parts of the world, the variation is huge. For example, the disease is almost 600 times more common in children and adolescents under the age of 15 in Finland than in low-risk countries such as China and Venezuela. But the numbers between different populations vary tenfold in Europe as well. Childhood type 1 diabetes is most prevalent in Finland, followed by Sweden in second place.

Photo: GoodShoot

Two thousand diabetic children
Ahmed Delli has analysed the children in the BDD study – Better Diabetes Diagnostics. In total, 1,988 children were included in his study. The children were classified into three groups depending on ethnic origin: Swedish origin; non-Swedish origin; and mixed origin (Swedish-Finnish or Swedish-other). "We used a strict definition for the classification. In order to fall into the Swedish group, for example, both the parents and the paternal and maternal grandparents had to have been born in Sweden. If one of them was from another country, the patient was classified into another group", explains Ahmed Delli.

Comparison with countries of origin
When Ahmed Delli compared how common the development of type 1 diabetes was in the non-Swedish group with how common it is in the countries where the children’s parents and paternal and maternal grandparents were born, he found that the risk was significantly higher in Sweden. "It is possible that the registration of children who develop type 1 diabetes is not complete in places like the Middle East, but the differences are so vast that this alone is not a satisfactory explanation", says Ahmed Delli.

Risk gene analysis
Several previous studies have found that immigration increases the risk of diabetes, but Ahmed Delli’s study was able to investigate further thanks to the information available in the BDD study. "We were also able to analyse the children’s risk genes for type 1 diabetes and how the pattern of antibodies looked at the time of the onset of the disease. This has never been done before", Ahmed Delli explains and continues: "Nine out of ten children who develop type 1 diabetes in Sweden carry one or both of the two most common risk variants.

The Swedish diabetes environment
Gene analysis showed that children without a Swedish background were more likely to not carry either of the two common risk genes than those with a Swedish background. "Within that [foreign] group there may be completely different risk variants, but that doesn’t explain the differences between groups relating to how many fall ill", says Ahmed Delli. "The fact that the risk of type 1 diabetes for children of foreign origin is doubled when they are born and grow up in this country strongly suggests that something in the Swedish environment causes this elevation of risk. This is why it is so important to try to identify the cause. We need to increase our understanding of the causal mechanisms and also try to identify ways to prevent the disease", he concludes.

Link to the article in Pediatric Diabetes:

Type 1 diabetes patients born to immigrants to Sweden increase their native diabetes risk and differ from Swedish patients in HLA types and islet autoantibodies

www3.interscience.wiley.com/journal/123317306/abstract

For more information: Ahmed Delli (English): +46 40 39 11 33,

Ahmed.Delli@med.lu.seÅke Lernmark: +46 40 39 19 01, +46 70 616 47 79, Ake.Lernmark@med.lu.se

Last updated: April 23, 2010
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