Does berberine lower blood sugar?

Yes — berberine does lower blood sugar markers, but the effect is modest and the evidence is rated low certainty.

A meta-analysis of 20 randomised trials (n = 1,761) found that berberine reduced fasting glucose by 0.52 mmol/L, HbA1c by 4.48 mmol/mol, and a measure of insulin resistance (HOMA-IR) by 0.85, all versus placebo 3. Effects were larger in women, people with diabetes, and Asian participants — though those subgroup comparisons rest on fewer studies. A separate trial in people with type 2 diabetes found meaningful drops in both fasting and post-meal glucose alongside improved insulin sensitivity 1.

One important caveat: these trials compared berberine to placebo, not to metformin or other diabetes medications, so we don't know how it stacks up against standard treatment. There's also a newer trial of a modified berberine compound (berberine ursodeoxycholate) showing HbA1c reductions in type 2 diabetes 5, and a 2026 trial finding it reduced liver fat and visceral fat in people with obesity without diabetes 4 — suggesting the molecule does more than just nudge glucose.

The catch: berberine is pharmacologically active, not a casual supplement. It inhibits liver enzymes (CYP3A4/2D6) and can interact with statins, warfarin, ciclosporin, and many cardiovascular drugs — and carries a hypoglycaemia risk if combined with insulin or sulphonylureas.