An oral glucose tolerance test (OGTT) is the most commonly used method to diagnose diabetes mellitus from a drop of blood. It measures the ability of an organism to clear circulating glucose after ingestion of glucose bolus after an overnight fast. Although the dynamics of the blood glucose levels during the OGTT are well known, much less information about the metabolic changes in the target organs and the inter-organ communication are available. In our study, we investigated what is the fate of the sugar molecules in each organ and how it affects metabolic pathways in the body. Therefore, we performed the OGTT in mice using glucose with stable isotopic tracers (13C), analyzed 13C6-glucose tissue distribution and time profiles of metabolites and lipids across 12 organs and plasma. We found, that during the OGTT, the glucose use is turned on with specific kinetics at the organ level, but fasting substrates like β-hydroxybutyrate are switched off in all organs simultaneously. Timeline profiling of 13C-labeled fatty acids and triacylglycerols across tissues suggests that brown adipose tissue may contribute to the circulating fatty acid pool at maximal plasma glucose levels. We have created a virtual interactive atlas of metabolites (sugars, amino acids, lipids, etc.), which describes the interactions between organs after ingesting grape sugar. Metabolic fate of ingested glucose carbons was followed in 12 organs and plasma.

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Lopes M, Brejchova K, Riecan M, Novakova M, Rossmeisl M, Cajka T, Kuda O. Metabolomics atlas of oral 13C-glucose tolerance test in mice. Cell Rep. 2021 Oct 12;37(2):109833. DOI. PMID: 34644567 IF = 9,423