We debut a liquid chromatography-mass spectrometry (LC/MS) platform called the XenoScan, which is a metabolomics platform for xenometabolites (nonself-originating metabolites). This assay has 190 in-house standards with the majority enriched for microbe-derived metabolites. As a proof-of-principle, we used the XenoScan to discriminate genetic differences from cecal samples associated with different rat lineages, in addition to characterizing diabetes progression in rat model of type 2 diabetes. Complementing microbial sequencing data with xenometabolites uncovered novel microbial metabolism in targeted organisms.