The renal metabolic recognition of AGE by the toll-like receptor (TLR) which is a sensor for pathogen-associated molecular patterns common to bacterial components has been suggested as one candidate for the occurrence of diabetic nephropathy because as at least TLR2 and TLR4 are clearly detected in blood when diabetic nephropathy is established, and the blood AGE elevates the TLR2 and TLR4 levels in monocytes and glomeruli in diabetic nephropathy [8–13]. This evidence concerns the gene TLR4 and diabetic kidney disease.