The short answer
Possibly, by adding to metformin's sugar lowering. The studies used isolated berberine or a tablet of Berberis aristata extract standardised to 97% berberine HCl, not daruharidra (daru haldi) root or a classical medicine. In a small trial, that tablet, which also held hesperidin and chromium, lowered fasting sugar and HbA1c when added to metformin for 12 weeks.
In rats, berberine lowered metformin levels in the blood and raised them in the kidney. This has not been measured in people. If you take metformin, tell your prescribing doctor before you start berberine, and ask whether you should check your sugar more often, especially if you also take insulin or a sulfonylurea.
Metformin is sold in India as Glycomet and Glycomet SR, and with glimepiride as Glycomet-GP.
At a glance
| What was seen | How it may work | Direction | Evidence |
|---|---|---|---|
| Lower fasting sugar and HbA1c when added to metformin (97% berberine HCl extract with hesperidin and chromium)[1] | Added sugar lowering | More sugar lowering on top of metformin | RCT |
| HbA1c fell from 8.1% to 7.3% with add-on isolated berberine[2] | Sugar lowering | Adds to diabetes medicines | Small clinical study |
| Less metformin in the blood, more in the kidney (isolated berberine, rats)[3] | Blocks OCT1, OCT2 and MATE1, transporters that carry metformin | Changes where metformin goes; size of effect in people unknown | Animal |
No listing is not a clearance. A missing interaction here never means a combination is safe.
The evidence, study by study
Randomised trial in type 2 diabetes, 2021 RCT
Forty adults whose sugar was not well controlled on metformin alone either stayed on metformin or added one tablet a day for 12 weeks. The tablet held Berberis aristata extract standardised to 97% berberine HCl, plus hesperidin and chromium picolinate. In the add-on group fasting sugar fell from 145 to 128 mg/dL and HbA1c from 53.5 to 49.5 mmol/mol, and no side effects were recorded. The trial was small, open-label and single-centre, and the three ingredients cannot be told apart.[1]
Clinical study in type 2 diabetes, 2008 Small clinical study
In one arm of this study, 48 adults with poorly controlled type 2 diabetes took isolated berberine on top of their usual treatment for three months, with no comparison group. HbA1c fell from 8.1% to 7.3%. Across the study, 34.5% of participants had short-lived stomach upsets. The report does not say how many of the 48 were taking metformin.[2]
Rat and cell study, 2019 Animal
Rats were given metformin and isolated berberine together by mouth, and berberine was tested on cells carrying the transporters that move metformin in and out of tissues. Berberine blocked OCT1, OCT2 and MATE1. Blood levels of metformin and the amount cleared in urine and bile went down, while the amount in kidney tissue went up. Animal results cannot tell us how much this changes metformin in people.[3]
What your doctor may watch for
- Blood sugar, and any episode of low sugar, especially if you also take insulin or a sulfonylurea such as glimepiride. The metformin label warns that low sugar is more likely with these.[4]
- Stomach upset, which about a third of people in one berberine study reported.[2]
- Kidney function.[4]
What to tell your prescribing doctor
You can read this out, or show them this page:
“I am taking, or planning to take, berberine (name of product, how much berberine it contains, dose) along with metformin. In one small trial a berberine tablet lowered sugar further when added to metformin, and in rats berberine changed metformin levels. Should I check my sugar more often, and should anything else be tested?”
Withheld until review
Questions people ask
Is daruharidra the same as berberine?
No. Berberine is one compound found in daruharidra (Berberis aristata, also called Indian barberry or tree turmeric) and in other plants such as barberry, goldthread and goldenseal. The studies here used isolated berberine or a concentrated extract, so how much berberine a daruharidra powder or classical medicine gives is not known from them.[5][1]
Related
Berberine and statins
Isolated berberine slowed CYP3A4, an enzyme the simvastatin label warns about, but a 7-day test found no clear change in simvastatin levels.
InteractionBerberine and levothyroxine
Not tested in people. Two rat studies used high doses of thyroid hormone, which says little about levothyroxine tablets, a drug with little margin.
ConditionType 2 diabetes (sugar): what Ayurveda offers
Some herbs, such as methi and karela, lowered HbA1c a little in trials. Taken with diabetes medicines, they can add to the risk of low sugar.
InteractionKarela (bitter gourd) and diabetes medicines
Added to metformin and dapagliflozin, a karela extract lowered HbA1c further in a 2026 study. With insulin or sulfonylureas, low sugar is the worry.
Sources
- Sartore G, Ragazzi E, Antonello G, Cosma C, Lapolla A. Effect of a new formulation of nutraceuticals as an add-on to metformin monotherapy for patients with type 2 diabetes and suboptimal glycemic control: a randomized controlled trial. Nutrients. 2021;13(7):2373. PMID 34371883.
- Yin J, Xing H, Ye J. Efficacy of berberine in patients with type 2 diabetes mellitus. Metabolism. 2008;57(5):712-717. PMID 18442638.
- Shi R, Xu Z, Xu X, Jin J, Zhao Y, Wang T, Li Y, Ma Y. Organic cation transporter and multidrug and toxin extrusion 1 co-mediated interaction between metformin and berberine. Eur J Pharm Sci. 2019;127:282-290. PMID 30428337.
- Metformin hydrochloride tablets (immediate release), US prescribing information (DailyMed, NuCare Pharmaceuticals).
- Memorial Sloan Kettering Cancer Center. About Herbs: Berberine.
Updated 4 November 2026
Taking berberine with other medicines? A vaidya can check your full list.
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