Herbal Nutraceuticals

What randomized controlled trials have compared herbal nutraceutical supplements versus metformin or placebo for lowering HbA1c, and what were their sample sizes and outcomes?

Randomized controlled trials (RCTs) have tested several herbal nutraceuticals—most extensively berberine—and a handful of multiherb formulas against placebo and, less often, against metformin; the evi...