Serum Metabolomics Reveals Potential Differences in Gut Microbiota–Associated Metabolites in Twins Discordant for Type 1 Diabetes

We investigated serum metabolites in monozygotic (MZ) and dizygotic (DZ) twins discordant for type 1 diabetes (T1D) to explore potential environmental factors, with a focus on differences in gut microbiota–associated metabolites that may influence T1D. Serum samples from 39 twins discordant for T1D were analyzed using a semi-targeted metabolomics approach via liquid chromatography–high-resolution tandem mass spectrometry. Statistical analyses identified significant metabolites (P < 0.1) within three groups: all twins (combined group [All]), MZ twins, and DZ twins. Thirteen metabolites exhibited significant differences between individuals with T1D and those without T1D. Across all groups, 3-indoxyl sulfate and 5-hydroxyindole were significantly reduced in individuals with T1D. Carnitine was reduced, and threonine, muramic acid, and 2-oxobutyric acid were significantly elevated in both All and MZ groups. Allantoin was significantly reduced and 3-methylhistidine was significantly elevated in All and DZ groups. These findings suggest metabolite dysregulation associated with gut dysbiosis was observed. However, further validation of our findings in a larger cohort is needed. ARTICLE HIGHLIGHTS We believed this cohort of twins discordant for type 1 diabetes (T1D) would allow for control over genetic variability to examine environmental factors. We aimed to identify differences in microbial and microbiota-associated metabolites in twins discordant for T1D to examine the effect of the gut microbiome on T1D. Thirteen metabolites were identified as significantly different. Our results show dysregulation of several microbial metabolites in twin pairs, suggesting the role of the gut microbiome in T1D pathogenesis.