The role of NOXs in DKD was supported by the finding of increased expression of the pro-oxidant NADPH oxidase subunits which were observed on the gene and protein level in renal cells including podocytes, mesangial and endothelial cells with concomitant downregulation of antioxidant enzymes (e.g., glutathione peroxidase) when exposed to high glucose conditions [30,31]. Here, FMO5 is linked to diabetic kidney disease.