Metformin
Oral diabetes drug. Used in PCOS for insulin resistance and (off-label) weight.
First-line for type 2 diabetes. Off-label for PCOS, prediabetes, and weight management. 500-2000mg daily, titrate slowly to reduce GI side effects. Cheap ($5-10/month generic). Considered safe long-term; B12 monitoring recommended after 5+ years of use.