In that case Berberine should do the same thing, and it’s a supplement that doesn’t have Metformin’s side effects.
Diet can beat insulin resistance, but it takes a very strict diet with practically no carbs, little protein, and lots of non-processed fats; some people can handle it, others get very sick from it. Keto+supplements (turmeric, berberine, MCTs) is a safer course, in general.
Berberine has some known interactions:
https://www.webmd.com/vitamins/ai/ingredientmono-1126/berberine