Metformin is a terrible approach to slowing aging in comparison to, say, mTOR inhibition. Slowing aging in this way, by manipulating the operation of an aged cellular metabolism without repairing the underlying damage that causes aging, is in turn a terrible approach to the treatment of aging. Yet metformin attracts a great deal of interest. I believe that most people simply don't care about effect size and reliability. Most popular science materials don't discuss these points, thus putting every intervention on the same footing in the minds of much of the public. Yet effect size and reliability are the very heart of the matter.
The animal data on metformin shows it to be unreliable when it comes to effects on life span; results from different studies and different groups are quite varied. The one large human study to examine mortality and life span looked at people with type 2 diabetes, not healthy individuals. It is known that metformin disrupts the operation of mechanisms needed for benefits to health to arise from regular exercise - a significant issue. Lastly, even if taking the human data at face value, the effect size is really just not large enough to care about. Nothing in the research noted here changes any of this.
Previously, the only biochemical pathway that was known to be activated by metformin was the AMPK pathway, which researchers discovered stalls cell growth and changes metabolism when nutrients are scarce, as can occur in cancer. But the scientists believed more pathways than AMPK might be involved. The scientists developed a novel screening platform to examine kinases, the proteins that transfer phosphate groups, which are critical on/off switches in cells and can be rapidly flipped by metformin. Using this technology, the researchers were able to decode hundreds of regulatory "switch-flipping" events that could affect healthy aging.
The results revealed that metformin turns on unexpected kinases and pathways, many independent of AMPK. Two of the activated kinases are called Protein Kinase D and MAPKAPK2. These kinases are poorly understood, but are known to have some relation to cellular stress, which could connect them to the health-span- and life-span-extending effects observed in other studies. In fact, metformin is currently being tested in multiple large-scale clinical trials as a health-span- and life-span-extending drug, but the mechanism for how metformin could affect health and aging has not been clear. The current study indicates that Protein Kinase D and MAPKAPK2 may be two players in providing these therapeutic effects, and identifies new targets and cellular processes regulated by AMPK that may also be critical to metformin's beneficial effects.
"The results broaden our understanding of how metformin induces a mild stress that triggers sensors to restore metabolic balance, explaining some of the benefits previously reported such as extended healthy aging in model organisms taking metformin. The big questions now are what targets of metformin can benefit the health of all individuals, not just type 2 diabetics."