Berberine is an alkaloid extracted from various plants used in traditional Chinese medicine. It's primarily used to reduce insulin resistance and improve biomarkers of type II diabetes such as fasting glucose and glycated hemoglobin. Berberine can activate an enzyme called Adenosine Monophosphate-Activated Protein Kinase (AMPK) while inhibiting Protein-Tyrosine Phosphatase 1B (PTP1B), thus increasing insulin sensitivity. Other possible mechanisms of action include protecting and β-cells, regulating hepatic gluconeogenesis, and reducing inflammatory cytokine signaling.
Human and animal research suggests that 1500mg of berberine, taken in three doses of 500mg each, is equally effective as taking 1500mg of metformin or 4mg glibenclamide, two pharmaceuticals for treating type II diabetes. Effectiveness was measured by how well the drugs reduced biomarkers of type II diabetes. It should be noted that although there's a fair bit of research suggesting strong effects of berberine for reducing biomarkers of type II diabetes, it's is still less supported by research than many pharmaceuticals and it's unclear what its long-term effects on mortality and complications are.
Berberine has a high potential to interact with medications, and some interactions may be severe. It is generally safe in normal doses, but more long-term research on its safety is needed. Gastrointestinal upset can occur when high doses are used, and due to its ability to reduce blood sugar, it may increase the risk for hypoglycemia in high doses, though this isn't a common occurance.
Tentatively, yes, but a doctor's guidance is highly recommended. Berberine has been the subject of much research and seems to be potent like many pharmaceuticals, but unlike the most well-researched pharmaceuticals, its long-term safety and frequent adverse effects haven't been sufficiently evaluated.