In the present study, oxidative stress markers, including urinary levels of 8-OHdG and serum levels of d-ROMs, were significantly suppressed, while the expression levels of GPx1, SOD1, and CAT mRNA, which encode antioxidant enzymes, in the colonic mucosa were increased by astaxanthin intake in AOM-injected db/db mice. This evidence concerns the gene GPX1 and infectious otitis media.