Stinging Nettle Root and Blood Sugar: What the Research Shows
By Real Herbs Editorial Team · Published October 2026 · Updated October 2026 · 6 min read
Key takeaway: The human trials of nettle and blood sugar we found were in adults with type 2 diabetes, and they used leaf extract or mixed herbal formulas, not nettle root. Two pooled analyses of these trials report a fall in fasting blood glucose of about 17 to 18 mg/dL, while the two differ on HbA1c, and the individual trials varied widely. We found no trial of nettle root alone on blood sugar, so these results should not be read as results for root.
Nettle is often described as a herb for blood sugar, so it is fair to ask whether that applies to nettle root (Urtica dioica). This guide sets out what the trials measured, which plant part they used, what the pooled analyses report, and what to do if you have diabetes or take diabetes medicines.
Disclosure: Real Herbs sells a stinging nettle root extract. We report each study as it was published, and none of the studies below tested this product.
Which part of nettle was studied
Nettle leaf and nettle root are different herbal materials with different traditional uses. The EMA lists the root for urinary symptoms related to benign prostatic hyperplasia (BPH) ([1]). The blood sugar trials below are mostly of leaf extract or of mixed products, which is why they are kept separate from the prostate research. Our root versus leaf guide explains the difference.
What the human trials report
The trials in the table were all in adults with type 2 diabetes. Where the abstract names the plant part, it is leaf; the others do not name it.
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| Trial | People and length | Product | Result reported |
|---|---|---|---|
| Kianbakht 2013 | 92 people (46 per group); 3 months | Nettle leaf extract, 500 mg every 8 hours, added to usual diabetes medicines | Fasting glucose, 2-hour glucose and HbA1c were lower than with placebo (p < 0.001, 0.009 and 0.006); no significant change in blood pressure, creatinine or liver enzymes ([2], PMID 24273930) |
| Khalili 2017 | 60 people; 90 days | Mix of nettle leaves, milk thistle seed and olibanum resin | Fasting glucose, HbA1c and triglycerides were lower than with placebo; no significant effect on cholesterol or blood pressure ([3], PMID 29228792) |
| Parham 2020 | 76 adults (two groups of 38); 12 weeks | Capsules in which nettle leaf was 20% of a mix with other herbs | Fasting and 2-hour glucose, HbA1c and insulin resistance fell; the authors report an HbA1c fall of 1.31% for the mix ([4], PMID 32042381) |
| Namazi 2011 | 50 people; 8 weeks | Hydroalcoholic nettle extract, 100 mg per kg of body weight a day in three portions (plant part not named in the abstract) | The inflammation markers IL-6 and hs-CRP were lower than in the control group ([5], PMID 22303583) |
Human trial The leaf extract trial authors note that nettle leaves have been reported to have insulin secretagogue, PPAR-gamma agonist and alpha-glucosidase inhibitory effects in laboratory work ([2], PMID 24273930). Three of the four products above were a leaf or leaf-containing mix, and the fourth did not name the part, so none of them tells us about nettle root.
What the pooled analyses report
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| Review | Trials included | Fasting blood glucose | HbA1c | Other findings |
|---|---|---|---|---|
| Ziaei 2020 | 8 trials, 401 people | Lower by 18.01 mg/dL (95% CI 30.04 to 5.97) ([6], PMID 31802554) | Lower by 0.77 percentage points, a change that was not statistically significant (95% CI 1.77 lower to 0.22 higher) | Insulin and an insulin-resistance index were not significantly changed |
| Tabrizi 2022 | 13 trials | Lower by 17.17 mg/dL (95% CI 26.60 to 7.73) ([7], PMID 34587883) | Lower by 0.93 percentage points (95% CI 1.66 to 0.17) | Triglycerides, C-reactive protein and systolic blood pressure were lower; insulin, total, LDL and HDL cholesterol and diastolic blood pressure were not significantly changed |
Both reviews note that results varied a great deal between trials: the statistical measure of variation (I²) was about 93% to 95% for fasting glucose ([6], PMID 31802554; [7], PMID 34587883). Ziaei and colleagues rated five of the eight trials as good quality, one as fair and two as poor, and concluded that nettle may help control fasting glucose while further studies are needed to confirm it ([6], PMID 31802554). The two reviews differ on HbA1c, which is a reminder that the pooled picture depends on which trials and products are included.
What about nettle root
We found no trial of nettle root alone that measured blood glucose or HbA1c. The EMA assessment report for nettle root sets out a traditional use for urinary symptoms of BPH ([1]), and a review of the antidiabetic and cardiovascular properties of the plant says that identifying the constituents and their exact mechanisms is needed before efficacy can be established ([8], PMID 30246639). Until root is studied directly, leaf results are best read as leaf results.
If you have diabetes or take diabetes medicines
- Do not replace treatment. No study cited here compares nettle with diabetes medicines or suggests stopping them.
- Tell your prescriber. The leaf extract trial added nettle to usual medicines, and no study of nettle root with diabetes medicines was found, so how they combine is not known. See our interactions guide.
- Keep monitoring. Carry on with the blood glucose and HbA1c checks your clinician has set, and report any changes.
- Check the product. Many “blood sugar” products are blends. Look for the plant part and the other herbs listed.
For general side effects and who should check first, see our safety guide.
Frequently asked questions
Does nettle root lower blood sugar?
We found no trial of nettle root alone that measured blood sugar. The trials that report lower fasting glucose used leaf extract or mixed herbal products.
How much did nettle lower blood sugar in the trials?
Two pooled analyses report a fall in fasting blood glucose of about 17 to 18 mg/dL on average, with wide differences between trials. They differ on HbA1c.
Can I take nettle with metformin or insulin?
No study of nettle root with diabetes medicines was found. Tell your prescriber before you start, and keep the glucose checks they have set.
Is nettle a substitute for diabetes medicine?
No. The trials added nettle to usual treatment, and none suggests stopping it.
Why do the pooled results vary so much?
The trials used different products, doses, plant parts and lengths of treatment. The reviews report high variation between them.
Are the trials of good quality?
In one review, five of eight trials were rated good quality, one fair and two poor. Most trials were small and short.
Does nettle leaf tea have the same effect as nettle root capsules?
They are different materials, and the research on each is separate. The blood sugar trials we found did not use nettle root.
Should I have my blood sugar checked before taking nettle?
If you have diabetes or risk factors for it, talk to your doctor first and keep your regular checks.
The bottom line
The blood sugar research on nettle is mostly leaf or mixed products in people with type 2 diabetes, and it varies from trial to trial. Nettle root has not been tested on blood sugar in the trials we found. If you have diabetes, treat nettle as something to discuss with your doctor and not as a replacement for your treatment.
Real Herbs Stinging Nettle Root Extract: 750 mg of 10:1 root extract per capsule (about 7,500 mg dried root equivalent), 100 vegetarian capsules. Backed by our 100-Day Money-Back Guarantee. Real Herbs sells this product. The trials and the EMA documents did not test this exact product.
Related reading
- Nettle root vs nettle leaf: key differences
- Nettle root and medicine interactions
- Nettle root side effects and who should avoid it
- Nettle root, blood pressure and heart health
References
- European Medicines Agency, Committee on Herbal Medicinal Products. Assessment report on Urtica dioica L.; Urtica urens L., radix. EMA/HMPC/322627/2023. Final, Revision 1, 22 January 2025. ema.europa.eu
- Kianbakht S, Khalighi-Sigaroodi F, Dabaghian FH. Improved glycemic control in patients with advanced type 2 diabetes mellitus taking Urtica dioica leaf extract: a randomized double-blind placebo-controlled clinical trial. Clin Lab. 2013;59(9-10):1071-6. PMID 24273930 · DOI 10.7754/clin.lab.2012.121019
- Khalili N, Fereydoonzadeh R, Mohtashami R, Mehrzadi S, Heydari M, Huseini HF. Silymarin, olibanum, and nettle, a mixed herbal formulation in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. J Evid Based Complementary Altern Med. 2017;22(4):603-608. PMID 29228792 · DOI 10.1177/2156587217696929
- Parham M, Bagherzadeh M, Asghari M, Akbari H, Hosseini Z, Rafiee M, Vafaeimanesh J. Evaluating the effect of a herb on the control of blood glucose and insulin-resistance in patients with advanced type 2 diabetes (a double-blind clinical trial). Caspian J Intern Med. 2020;11(1):12-20. PMID 32042381 · DOI 10.22088/cjim.11.1.12
- Namazi N, Esfanjani AT, Heshmati J, Bahrami A. The effect of hydro alcoholic nettle (Urtica dioica) extracts on insulin sensitivity and some inflammatory indicators in patients with type 2 diabetes: a randomized double-blind control trial. Pak J Biol Sci. 2011;14(15):775-9. PMID 22303583 · DOI 10.3923/pjbs.2011.775.779
- Ziaei R, Foshati S, Hadi A, Kermani MAH, Ghavami A, Clark CCT, Tarrahi MJ. The effect of nettle (Urtica dioica) supplementation on the glycemic control of patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Phytother Res. 2020;34(2):282-294. PMID 31802554 · DOI 10.1002/ptr.6535
- Tabrizi R, Sekhavati E, Nowrouzi-Sohrabi P, Rezaei S, Tabari P, Ghoran SH, et al. Effects of Urtica dioica on metabolic profiles in type 2 diabetes: a systematic review and meta-analysis of clinical trials. Mini Rev Med Chem. 2022;22(3):550-563. PMID 34587883 · DOI 10.2174/1389557521666210929143112
- El Haouari M, Rosado JA. Phytochemical, anti-diabetic and cardiovascular properties of Urtica dioica L. (Urticaceae): a review. Mini Rev Med Chem. 2019;19(1):63-71. PMID 30246639 · DOI 10.2174/1389557518666180924121528
Disclaimer: This article is for educational purposes only and is not medical advice. Talk with a qualified healthcare professional before starting any supplement, especially if you have a medical condition or take medication. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
