Primary Research · 2008
Efficacy of berberine in patients with type 2 diabetes mellitus
Yin J, Xing H, Ye J · Metabolism, 2008
Key finding
3-month RCT in newly diagnosed T2DM (n=84) found berberine 500mg three times daily reduced HbA1c, fasting glucose, and postprandial glucose comparably to metformin.
Abstract
PubMed · PMID 18442638 →Berberine has been shown to regulate glucose and lipid metabolism in vitro and in vivo. This pilot study was to determine the efficacy and safety of berberine in the treatment of type 2 diabetes mellitus patients. In study A, 36 adults with newly diagnosed type 2 diabetes mellitus were randomly assigned to treatment with berberine or metformin (0.5 g 3 times a day) in a 3-month trial. The hypoglycemic effect of berberine was similar to that of metformin. Significant decreases in hemoglobin A1c (from 9.5%+/-0.5% to 7.5%+/-0.4%, P<.01), fasting blood glucose (from 10.6+/-0.9 mmol/L to 6.9+/-0.5 mmol/L, P<.01), postprandial blood glucose (from 19.8+/-1.7 to 11.1+/-0.9 mmol/L, P<.01), and plasma triglycerides (from 1.13+/-0.13 to 0.89+/-0.03 mmol/L, P<.05) were observed in the berberine group. In study B, 48 adults with poorly controlled type 2 diabetes mellitus were treated supplemented with berberine in a 3-month trial. Berberine acted by lowering fasting blood glucose and postprandial blood glucose from 1 week to the end of the trial. Hemoglobin A1c decreased from 8.1%+/-0.2% to 7.3%+/-0.3% (P<.001). Fasting plasma insulin and homeostasis model assessment of insulin resistance index were reduced by 28.1% and 44.7% (P<.001), respectively. Total cholesterol and low-density lipoprotein cholesterol were decreased significantly as well. During the trial, 20 (34.5%) patients experienced transient gastrointestinal adverse effects. Functional liver or kidney damages were not observed for all patients. In conclusion, this pilot study indicates that berberine is a potent oral hypoglycemic agent with beneficial effects on lipid metabolism.
Abstract sourced from PubMed, a database of the U.S. National Library of Medicine. Displayed in the authors’ own words for context; our critique is in the sections below.
About the supplement
Berberine
Dose · mechanism · evidence grade · safety →
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How to read a study like this
The same questions worth asking about any research paper, not just this one. Worth a minute even if you trust the grade.
Who was studied, and do you resemble them?
Supplement effects often depend on baseline status. Vitamin D helps people who are deficient; iron helps people who are anemic. A result in people unlike you may not apply to you.
What was measured, and does it matter in daily life?
A study that shows a blood marker moved isn't the same as a study that shows people felt or functioned better. Ask what the outcome means in practice.
How large was the effect — not just whether it was significant.
'Statistically significant' only means the effect is unlikely to be zero. It doesn't tell you the effect is large enough to notice. Look for effect sizes, not just p-values.
Who paid for the trial, and what did they stand to gain?
Industry-funded trials are several times more likely to report positive results than independent ones. It's not usually fraud — it's subtle design and reporting choices. Weight accordingly.
Has anyone else replicated this?
Single positive trials are hypotheses. Replication by independent groups is what turns a hypothesis into reliable evidence. If the only positive trial is the one you're reading, wait.
Does the dose in the trial match what's being sold?
Supplement marketing routinely cites trials that used 5–10× the dose in the product. If the effective dose was 2 g/day and the capsule has 200 mg, expect roughly no effect.
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