Herbal Antidiabetic Ingredients vs Metformin

What randomized controlled trials exist comparing common herbal antidiabetic ingredients to standard therapies (metformin) for A1C reduction, and what do meta‑analyses show?

Randomized trials that directly pit single herbal antidiabetic ingredients against metformin are scarce; most randomized evidence tests herbs versus placebo or tests herbal formulas as add‑ons to metf...