This study aims to determine the role of urinary plasminogen, a serine protease that reflects damage to the glomerular filtration barrier, in the early detection of diabetic kidney disease in pediatric patients with type 1 diabetes mellitus (T1DM). Pediatric patients, who had been followed up with T1DM for at least 2 years, and healthy matched controls were included. The gene discussed is PLG; the disease is diabetes mellitus.