A Northwestern University-led study reported preclinical evidence that metformin’s glucose-lowering effects in mice are tied primarily to action in the gut rather than solely the liver. Published in Nature Metabolism, the work describes how metformin drives glucose utilization inside intestinal epithelium cells. The study found that metformin slows mitochondrial energy production in gut cells by inhibiting mitochondrial complex I, co-opting the intestines to function as a glucose “sink” that metabolizes extra sugar. The authors also report that phenformin and berberine appear to engage the same gut mitochondrial pathway. The findings provide a mechanistic bridge to gut-related clinical observations—such as attenuated postprandial glucose excursions and elevated intestinal glucose uptake—despite longstanding uncertainty around metformin’s full mechanism of action. For the market, it reinforces metformin’s relevance as a reference compound while deepening interest in gut-centric metabolic targeting. Next steps likely include translational confirmation in humans and exploration of whether mitochondrial modulation in intestinal epithelium could inform next-generation diabetes therapeutics beyond metformin and its class.