We performed a two‐sample Mendelian randomization analysis using cis eQTLs for decorin as instrumental variables and T1D/T1D with complications traits from the FinnGen GWAS study33 as outcomes (Figure 5B) and associated an eQTL‐regulating decorin transcription in fibroblasts with risk of diabetic nephropathy (Figure 5B). Here, DCN is linked to type 1 diabetes mellitus.