We investigated, using Mendelian randomisation, the direction and magnitude of the expected change in the risk of type 1 diabetes if IL2RA, IL6R and IL6ST were targeted, using variants identified as the most likely shared causal variant in co-localisation (rs61839660 for IL2RA gene expression, F=248; variant rs10908839 for IL6R gene expression, F=148; and variant rs7731626 for IL6ST expression, F=159). This evidence concerns the gene IL6ST and type 1 diabetes mellitus.