In this study, we applied the streptozotocin (STZ)-induced diabetic adrenomedullin gene knockout (AMKO) mice to clarify the role of adrenomedullin in the NADPH oxidase expression and its oxidative products in diabetic nephropathy, and we also investigated the relationship between adrenomedullin and the renin-angiotensin system that stimulates NADPH oxidase and oxidative stress. This evidence concerns the gene FMO5 and diabetic kidney disease.