Metformin-mechanisms of its glycemia-reducing effect.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic, animal, and clinical literature without systematic review methodology
PubMed 41389439 · doi:10.1016/j.pharmr.2025.100106
What was done
This narrative review synthesizes clinical, animal, and cellular evidence on the physiological and molecular mechanisms responsible for the glucose-lowering effects of metformin in type 2 diabetes.
What was found
The abstract reports no quantitative values or statistical effect sizes. Mechanistic findings summarized include: - Liver: Long-term metformin reduces hepatic gluconeogenesis through both AMPK-dependent and AMPK-independent mechanisms (including mitochondrial complex I and mitochondrial glycerophosphate dehydrogenase inhibition). - Skeletal muscle: Enhances glucose disposal, with proposed mechanisms including AMPK activation and anti-inflammatory pathways. - Kidney: Inhibition of renal gluconeogenesis may contribute to extraintestinal glucose lowering. - Gastrointestinal tract: Plays a critical role (intravenous metformin lacks short-term glycemic effects in humans). Proposed actions include reduced intestinal glucose absorption due to enterocyte complex I inhibition, enhanced glucose transport to the colon, and stimulation of GLP-1 secretion by L-cells, which suppresses hepatic gluconeogenesis via the gut-brain-liver axis.
Why it matters
It highlights that metformin's efficacy extends beyond direct hepatic gluconeogenesis inhibition to include essential contributions from skeletal muscle glucose disposal and diverse intestinal actions, particularly GLP-1-mediated signaling.
Limits
The abstract describes a narrative review without systematic search or meta-analytic methods. Additionally, it notes that many experimental animal and cellular studies utilized metformin doses higher than those used clinically in humans.
Cited by
- supports Metformin impairs mitochondrial complex I.