In an in-vivo study [36], patients with type 1 diabetes carrying IL-1RN*1/*1 genotype had 30 % lower levels of plasma IL-1Ra compared with levels in patients carrying the IL1RN*1/*2 genotype further suggesting an enhancing effect of IL1RN*2 allele on IL-1Ra circulating levels in healthy carriers. This evidence concerns the gene IL1RN and type 1 diabetes mellitus.