Metformin is the pharmaceutical version of Berberine [1] You can get Berberine without a prescription. Metformin has been used in the US for about 40 years and Berberine in Asia for about 3000 years, initially used to treat gut infections.

A couple things to note if you take either of those is that they put a heavy load on the liver and also deplete vitamin B12. It may be worth keeping an eye on liver enzymes if using either. Hydration is also important. I should also add that if you start doing either to stay near a restroom for the first few weeks.

[1] - https://examine.com/supplements/berberine/