At JDRF, we are dedicated to curing, treating and preventing type 1 diabetes. This means that many of our researchers are looking for better ways to identify those at risk of developing the condition, so that we can deliver treatment as early as possible.
A new paper from a JDRF-funded study in Munich, Germany, has added to this knowledge by investigating the relationship between low vitamin D levels and type 1 diabetes, and finding a possible indirect link between the two.
Vitamin D is a hormone that is commonly found in fish oil and egg yolk, and is synthesised naturally in the body by exposure to sunlight. Historically, vitamin D deficiency has been linked to rickets and kidney failure in the elderly, but more recently, a lack of vitamin D has been linked to type 1, with some debate over the potential for dietary supplementation of vitamin D to protect against the condition.
The Munich team classified children into three groups: those with ‘pre’ type 1, based on the presence of immune cells called autoantibodies, which are a known predictor of type 1; those with type 1; and those having no autoantibodies and therefore no diabetes.
They then tested vitamin D levels in all three groups and found the group with no autoantibodies had the highest level of vitamin D, followed by the pre-type 1 and type 1 groups, respectively, suggesting that low vitamin D is more common in children with type 1 than in those without.
Because of this, they highlight the potential for vitamin D deficiency to serve as an additional marker for risk of type 1.
This difference was only significant in the summer, when vitamin D levels rose in children without autoantibodies, but stayed low the other two groups. The researchers, led by Professor Anette-Gabriele Ziegler, suggest that a genetic susceptibility to low vitamin D levels, combined with reduced exposure to sunlight, may be behind this difference.
They also suggest that, rather than a direct link (such as type 1 being caused by low vitamin D), the vitamin D deficiency might be caused by elevated levels of autoantibodies, which in turn is a major factor in type 1 diabetes. Indeed, the researchers noted that among the children in the pre-type 1 group, variation in vitamin D levels did not affect the rate at which they later developed type 1 diabetes. This suggests that the two factors are linked, but not causally.
As a result, this research complements JDRF’s work into the environmental triggers of type 1. The TEDDY (The Environmental Determinants of Diabetes in the Young) study is tracking the diets and illnesses of young people at high risk of developing type 1, looking for potential triggers of the condition. Research that suggests that vitamin D is not a direct cause of type 1 will help validate the work if it finds a similar result.
The research was published in the journal Diabetologia.