Do berberine, chromium or cinnamon lower blood sugar?
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Short answer
The evidence is weak. Reviews of berberine, chromium and cinnamon report small glucose reductions, but the trials are short, small and inconsistent in quality, and none has shown a reduction in diabetes complications. The ADA Standards of Care state that supplementation with vitamins, minerals, herbs or spices is not recommended for glycemic benefits.
Three supplements dominate the blood sugar market: berberine, chromium and cinnamon. All three have published trials showing glucose reductions. All three have the same problem, which is that the trials are small, short, heterogeneous in quality and unable to say anything about whether anyone ended up healthier. The ADA Standards of Care state that dietary supplementation with vitamins, minerals such as chromium and vitamin D, or herbs and spices such as cinnamon, is not recommended for glycemic benefits.
What the reviews actually report
NCCIH summarizes the position for each. A 2021 review of 46 studies found berberine may have beneficial effects on lowering blood glucose and reducing insulin resistance in type 2 diabetes, though the studies were mostly conducted in Chinese populations and were of variable quality. A 2022 review of 16 studies suggested chromium may improve HbA1c, fasting glucose and insulin resistance in type 2 diabetes. A 2019 review of 16 studies reported that cinnamon reduced fasting glucose and insulin resistance in prediabetes and type 2 diabetes, with findings varying by study quality.
| Supplement | What reviews suggest | What is missing |
|---|---|---|
| Berberine | Possible glucose and insulin resistance reduction | Outcome data, quality trials outside one region, product consistency |
| Chromium | Possible small HbA1c and glucose reduction | Long term safety, benefit in people without deficiency |
| Cinnamon | Possible fasting glucose reduction | Consistency across trials, dose standardization |
| Alpha-lipoic acid | No better than placebo for blood sugar in a 2019 review | Benefit is in neuropathy pain, not glycemia |
Why a small glucose drop is not a treatment
Metformin, lifestyle programs and the newer glucose lowering drugs are recommended because trials followed thousands of people for years and measured what happened to them: diabetes incidence, kidney function, heart attacks, deaths. Nothing comparable exists for berberine, chromium or cinnamon. A supplement that moves a laboratory number by a small amount in a twelve week trial has not been shown to prevent a single complication, and calling berberine natural metformin misrepresents the evidence in both directions.
Safety is not automatic either
NCCIH notes that chromium at large doses has been linked to stomach pain, kidney damage, liver damage and muscle problems, and that long term effects are inadequately studied. Berberine commonly causes nausea, diarrhea, bloating and constipation, and it should not be used in pregnancy or breastfeeding. Cassia cinnamon contains coumarin, which can worsen liver disease in susceptible people, and doses above about 6 g daily are not considered safe. Supplements are also not tested for potency before sale in the United States.
If you want to spend money on your glucose, spend it on the things with outcome data: a structured lifestyle program, resistance training, treating sleep apnea, and medication where it is indicated. If you choose to try a supplement anyway, tell your clinician, avoid it in pregnancy, avoid it with liver disease, and set a stop date and a repeat A1C so you can find out whether it did anything for you.
The clinical detail
Berberine has recognized potential for drug interactions and should be checked against a full medication list rather than assumed safe. Any agent that lowers glucose adds hypoglycemia risk when combined with insulin or a sulfonylurea, so doses of those drugs may need review.
Dietary supplements in the United States are not reviewed by the FDA for effectiveness before they are sold, and label content and actual content can diverge, so an independent third party certification mark is a minimum reasonable filter. NCCIH describes clinical berberine doses in the region of 200 to 1,000 mg daily, advises limiting supplemental magnesium to 350 mg daily unless a clinician says otherwise, and notes that cassia cinnamon is not considered safe above about 6 g daily because of its coumarin content.
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Sources
- Diabetes and Dietary Supplements: What the Science Says. National Center for Complementary and Integrative Health, NIH
- Standards of Care in Diabetes 2026, clinical guideline summary. American Diabetes Association, summary via Guideline Central
- Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. New England Journal of Medicine. PMID 11832527
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