Nature Metabolism, Published online: 08 May 2026; doi:10.1038/s42255-026-01532-wMetabolomic analysis of plasma from metformin-treated humans, together with mechanistic studies in mouse models, reveals that metformin selectively inhibits mitochondrial complex I in the intestinal epithelium. This mechanism unifies multiple clinical effects of metformin, including enhanced intestinal glucose use, improved postprandial glycaemic control and increased production of GDF15 and N-lactoyl-phenylalanine.
