Blue eyes and fair skin may increase risk for Type 1 diabetes
MedWire News: Having blue eyes, and to a lesser extent fair skin, increases a person's risk of having Type 1 diabetes, suggest results from an Italian study.
Acting on a previous observation that the frequency of blue eyes and fair skin is significantly more common in northern European Caucasians with Type 1 diabetes than in the nondiabetic population, Paolo Pozzilli (University Campus Bio-Medico, Rome) and colleagues investigated this phenomenon further in Lazio and Sardinia in Italy.
They assessed iris color and skin type (by melanin quantification) in 281 consecutive patients with Type 1 diabetes (178 Lazio; 103 Sardinia) and 298 controls (181 Lazio; 117 Sardinia).
In the group from Lazio, 21% of the patients with Type 1 diabetes had blue eyes compared with 9% of the controls. Similarly, significantly more Type 1 diabetics than controls had fair skin (Melanin index 0-150), at 50% versus 35%.
In the participants from Sardinia, blue eyes were significantly more common in the diabetic patients compared with controls, at 5.8% versus 2.6%, whereas skin fairness did not differ significantly between the two groups.
When the collected data was pooled, having blue eyes, but not fair skin, was associated with a significant 2.2-fold increased risk for Type 1 diabetes in the whole population.
Pozzilli and colleagues suggest that their results indicate that ultraviolet B irradiance is unlikely to have a demonstrable effect on the incidence of Type 1 diabetes, due to the lack of a significant association between diabetes and skin type.
Instead, they propose that the differences in eye and skin color observed between patients with Type 1 diabetes and controls may have more to do with differences in genetic ancestry.
The authors write in the journal Diabetes/Metabolism: Research and Reviews that "it should be of interest to evaluate the risk of blue eyes associated with HLA alleles of susceptibility or other genetic predisposition markers," for Type 1 diabetes.
They explain that "there are no studies showing that the loci linked with different eye color are risk loci for Type 1 diabetes. However, in a preliminary report we have evaluated a possible association between different single nucleotide polymorphisms of the OCA2, MC1R, and MATP genes and the eye color and the fair skin in Type 1 diabetes subjects."
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By Helen Albert