Metformin is a widely used drug for diabetes management that has shown certain benefits, but its long-term effects are uncertain. The drug is known to cause photosensitivity and GI discomfort and may reduce the utilization of B12.
In a study on the effects of metformin supplementation on the lifespan of Fisher 344 rats, no significant lifespan extension was observed. While it's important to standardize dosage, it may be more effective to mix metformin into the animals' food rather than injecting them with it directly.
The speaker discusses the side effects he observed with metformin, such as skin reactions and gastrointestinal discomfort, and compares it to his positive experience with berberine which alleviated those issues.