Chandler Marrs, PhD, has written an article for Hormones Matters website about the potentially damaging effects of the drug Metformin.
Metformin is used by many people to manage blood sugar and insulin resistance.
If the article is right then other approaches need to be taken, as the risk to mitochondrial health and B12 deficiency is quite worrying.
I include this here on my website because mitochondrial health is critical to thyroid hormone action.
I know some people are trying to use more natural approaches like Berberine extracted from herbs instead of using Metformin.
Anyway, here is the article. Please make up your own minds: