The Effect of Metformin Treatment on the Circulating Proteome

ObjectiveMetformin is one of the most used drugs worldwide. However, its mechanism of action remains uncertain. Given the potential to reveal novel insights into the pleiotropic effects of metformin treatment, we aimed to undertake a comprehensive analysis of circulating proteins. Research Design and MethodsWe analysed 1195 proteins using the SomaLogic platform in 1175 participants, using cross- sectional data from the GoDARTS and DCS cohorts; 450 proteins using the Olink platform in 784 participants, using cross-sectional data from IMI-DIRECT; and combined longitudinal data from the IMPOCT, RAMP and S3WP-T2D cohorts with 372 proteins in 98 participants using the Olink platform. Finally, we performed systems level analysis on the longitudinal OLINK data to identify any possible relationships for the proteins changing concentration following metformin exposure. ResultsOverall, 97 proteins were associated with metformin exposure in at least one of the studies (Padj<0.05), and 10 proteins (EpCAM, SPINK1, t-PA, Gal-4, TFF3, TF, FAM3C, COL1A1, SELL, CD93) were associated in two independent studies. Four proteins, REG4, GDF15, REG1A, and OMD were consistently associated across all studies and platforms. Gene-set enrichment analysis revealed that the effect of metformin exposure was on intestinal tissues. In the longitudinal analysis 18% of proteins were significantly altered by metformin. ConclusionsThese data provide further insight into the mechanism of action of metformin, potentially identifying novel targets for diabetes treatment, and highlight the need to account for metformin exposure in proteomic studies and where protein biomarkers are used for clinical care where metformin treatment will generate false positive results. HighlightsO_LIIn the most comprehensive proteomic analysis of metformin exposure to date, we showed 97 proteins to be associated with metformin exposure in at least one study. C_LIO_LI14 proteins were consistently associated with metformin exposure in 2 or more platforms or studies. C_LIO_LIGene enrichment analysis shows that the strongest protein set is of intestinal origin. C_LIO_LIThese data provide further insight into the mechanism of action of metformin, potentially identify novel targets for diabetes treatment and highlight the need to account for metformin exposure in proteomic studies and where protein biomarkers are used for clinical care. C_LI