Twins of parents with type 1 diabetes are at greater risk of developing the condition compared to other siblings, according to an international study.
The findings from the TrialNet programmen, a long-term programme funded in part by JDRF, were based on a three-year period. They applied to both identical and non-identical twins who were already identified as being at greater risk of type 1 diabetes.
Blood samples were collected from 630 non-identical twins and 288 identical twins, among a total of 48,000 siblings of people living with type 1 diabetes. These were then retaken either one or two times every 12 months.
The study team were checking for signs of autoantibodies which precede type 1 diabetes. Autoantibodies are part of the immune system and can become problematic as they are trained to destroy cells in our own body. Previous research has found that autoantibodies are often present in the body up to many years before the development of type 1 diabetes. People who have more than one type of autoantibody are at greater risk of the condition.
According to the new TrialNet results, identical twins with multiple autoantibodies at the initial screening had a 69% increased risk of developing type 1 diabetes, while non-identical twins had a similar 72% increased risk, and other siblings had a significantly lower 47% greater risk.
In participants with one type of autoantibody at the start, the risk of type 1 diabetes stood at 69% for identical twins, whilst being much lower at 13% for non-identical twins, and 12% for other siblings.
“These results reinforce previous findings that twins are at greater risk of developing type 1 diabetes than other siblings. The average age for initial screening was 11 however, and so these results may not be applicable to twins diagnosed at all ages,” said a JDRF reviewer.
“In their paper, the researchers suggest that the difference in risk for twins versus other siblings might be due to differences in what they’re exposed to. Twins share the same environment in the womb and almost exactly the same environment shortly after birth. Other siblings however experience the womb and external environment at different times from each other, and so are exposed to different things, which might alter the risk of developing type 1 diabetes.”
Now the researchers aim to explore whether the risks change over a longer period of time.
The study was published in the journal Diabetes Care.