To do so, we characterized intra‐ and interassay and intraindividual variability in the commercially available immunoassays and used these to compare urinary concentrations of AGT, MMP‐7, BMP‐7, and gremlin‐1 in people with type 1 diabetes and DKD to those without kidney disease as well as those with new‐onset type 1 diabetes. Here, BMP7 is linked to type 1 diabetes mellitus.