Study reveals metformin turns intestinal cells into a glucose sink

Scientists have uncovered that metformin transforms the gut into a major site of glucose absorption, thereby decreasing blood sugar levels. The discovery stems from experiments in mice where the researchers replaced the drug-sensitive mitochondrial complex I with a yeast enzyme that resists metformin; when respiration continued, the drug no longer lowered glucose, indicating that mitochondrial inhibition drives the effect.

By blocking oxygen use in gut cells, metformin forces them to rely on a sugar-intensive metabolic route, effectively turning the intestine into a glucose sink. This mechanism aligns with early French studies from 1989 and later imaging that showed the gut lighting up on PET scans after metformin dosing. The research, led by Navdeep Chandel at Northwestern University, was published in Nature Metabolism and suggests that targeted mitochondrial inhibition in specific tissues may have therapeutic benefits.

It also adds nuance to the drug’s proposed anti-aging properties, which some had linked to mitochondrial enhancement. Overall, the study reshapes understanding of how one of the world’s most prescribed diabetes medicines works.