If the plan denies the request but has other similar medications on its formulary, you can have a discussion with your doctor about whether one of the covered drugs might work for you
Subst Use Misuse 38:15751614 Algire C, Moiseeva O, Deschnes-Simard X, Amrein L, Petruccelli L, Birman E, Viollet B, Ferbeyre G, Pollak MN (2012) Metformin reduces endogenous reactive oxygen species and associated DNA damage
Berberine doesnt work if you eat McDonalds every day. As for who should skip the supplement, that group includes pregnant women or women who are breastfeeding (berberine can be transmitted through the placenta and may harm a fetus)
The calculator handles this automatically: you enter the mg quantity of the vial and the volume of bacteriostatic water, and the tool does the math