Berberine

Berberine is a plant alkaloid with unusually solid human evidence for a botanical: multiple trials show meaningful reductions in blood glucose and improvements in lipids, working partly through the energy-sensing enzyme AMPK.

Its glucose-lowering effect has even been compared to some diabetes medications in trials, making it one of the better-evidenced supplements for metabolic health. The trade-off is common gut upset (splitting doses helps) and meaningful drug interactions, so medical advice matters, especially alongside glucose-lowering medication.

Sources

• PubMed: berberine blood glucose lipids AMPK diabetes (research overview)