Metformin is a medication that helps cells become more sensitive to insulin. As you probably know, insulin is not an ovarian hormone. It is the hormone that almost every cell in the body needs to receive glucose sugar from the bloodstream. While it's hard to say which comes first, insulin insensitivity or PCOS, there is no doubt that PCOS and especially weight gain in PCOS is a condition in which cells all over the body put up biological barriers to the action of insulin. That's because insulin carries glucose into the cell. The cell then burns the glucose for energy, and the free radicals released by the mitochondrial "fire" can damage the cell. Cells resist insulin to prevent free radical damage.
But the pancreas keeps making more and more insulin to get blood sugar levels down, and cells all over the body become more and more resistant-except in the ovaries. The ovaries can't resist insulin. Sugar pores into their tissues and all that energy is put to an unusual use: Excess sugar stimulates the ovaries to make testosterone. Metformin makes cells all over the body except in the ovaries more sensitive to insulin. All the other tissues start doing their fair share of receiving blood sugar, and the ovaries don't make as much testosterone. When a woman's body makes less testosterone, there is less hair growth, less acne, and fewer mood swings. And through a complicated series of steps, there is also greater opportunity for ovulation.
There is very little downside to using metformin. It's not a "natural treatment for PCOS," but it has very few side effects except in a small number of women who have severe type 2 diabetes with dehydration as a complication. These women can't use metformin. For many women with PCOS, however, metformin amplifies the benefits of calorie-reduction and diet. It gets sugar out of the bloodstream, and stops a vicious cycle of high blood sugar, insulin resistance, testosterone production, failure to ovulate, and even higher blood sugars. Not every woman who has PCOS will resume normal periods with ovulation after taking the drug, but metformin is the very simplest and safest, not to mention least expensive, medication for polycystic ovarian disease.