In a sub-group of patients with type 1 diabetes blood was drawn at time of and after diagnosis, with a mean time between samplings 1.3 ± 0.5 years (n = 42), the trajectory of circulating Cystatin C, MMP-9, lipocalin-2 and FGF21 was analysed. This evidence concerns the gene FGF21 and type 1 diabetes mellitus.