In this cohort of long-time follow-up (median 18 years) of patients with type 1 diabetes, with and without diabetic nephropathy, we found that patients with an increased urinary IgM excretion had a higher mortality from CV causes, and higher disease progression rate to ESRD compared with patients with low urinary IgM excretion. This evidence concerns the gene CD40LG and type 1 diabetes mellitus.