Cinnamon sticks, plain capsules and a bowl of golden powder on an oak table

Glucose Support Supplements: What the Evidence Says About Cinnamon, Chromium, Berberine and Alpha-Lipoic Acid

Key Takeaways

  • "Glucose support" is label language, not a medical category. In the US the FDA does not approve supplements or their claims before sale, and in the UK a food supplement cannot claim to act on a disease.[1][2]
  • The ADA's 2026 Standards say supplements such as chromium and cinnamon are "not recommended for glycemic benefits".[3]
  • Pooled trials show small average changes in fasting glucose for cinnamon, chromium and berberine, with very wide spread between trials for cinnamon and chromium, and mostly Chinese trials for berberine. For alpha-lipoic acid the changes were below the clinically important threshold.[4][5][6][7]
  • Berberine should not be used in pregnancy, while breastfeeding or in infants, and cassia cinnamon carries a coumarin limit for the liver.[8][9]
  • If you take insulin, gliclazide or metformin, tell your pharmacist before adding any supplement.[10][3]

Glucose support is a phrase you will see on supplement labels and on the pages that sell glucose support supplements. The old guides to glucose support promised that cinnamon, chromium, berberine and alpha-lipoic acid would keep blood sugar in check. We went back to the pooled trials, the ADA 2026 Standards, NCCIH, the FDA and UK rules, and the NHS medicine pages to see what the evidence says for each of the four.

The short version: the average changes in trials are small, the trials disagree with each other, and neither the ADA nor Diabetes UK recommends supplements of this kind for blood sugar. Each one also has a safety point worth knowing before you buy.

This guide is general education. If you use insulin or other glucose medicines, follow the plan your diabetes team gave you.

What is glucose support?

It is a marketing phrase. In the US a claim of this kind is a structure/function claim, which the FDA describes as a claim about the role of an ingredient in the structure or function of the body. Such claims "are not approved by FDA and do not require FDA evaluation before they are used in dietary supplement labeling". The label must carry the FDA disclaimer that the product is not meant to act on any disease.[1] The FDA also says it "does not have the authority to approve dietary supplements before they are marketed". It can act only after a product is on sale.[1]

In the UK the same product is sold as food. Government guidance says food supplements "are not medicinal products". Their use is not meant to act on disease in humans. The label must say "food supplement" and warn you not to exceed the daily dose.[2] A herbal medicine that claims to act on a major health condition, which is the MHRA's phrase, needs a full marketing authorisation, not the simpler traditional herbal registration.[2]

Diabetes UK adds a plain warning: phrases such as "natural", "herbal" and "derived from plant" do not necessarily mean "safe".[11]

Can diet and movement do more than a supplement?

Yes, by a wide margin. The ADA's 2026 Standards of Care have one recommendation on supplements and blood sugar, number 5.16. Micronutrients such as magnesium or chromium, and herbs or spices such as cinnamon and aloe vera, are "not recommended for glycemic benefits". The text behind it says there is insufficient evidence for routine use of cinnamon, curcumin, aloe vera or chromium to improve glycemia.[3] That sentence cites the newest cinnamon pooled analysis from 2024. The ADA read it and still wrote "insufficient".[3]

Compare that with what the ADA does recommend. Nutrition therapy from a registered dietitian is linked with A1C changes of 0.3 to 2.0 percentage points (about 3.3 to 22 mmol/mol) in type 2 diabetes and 1.0 to 1.9 percentage points (about 11 to 21 mmol/mol) in type 1. The ADA asks for 150 minutes or more of moderate to vigorous activity a week, spread over at least 3 days.[3] Our guide to building a balanced plate covers the plate method, and our fibre guide has the trial numbers for fibre.

Cinnamon as a kitchen spice is a different story. The ADA's own table suggests herbs and spices, cinnamon among them, to season food instead of salt.[3] Diabetes UK says vitamin and mineral supplements have no clear benefits for people with diabetes unless you have a deficiency or your doctor prescribes them.[11]

What does the evidence say about cinnamon?

NCCIH, part of the US National Institutes of Health, puts it in one line: "It's unclear whether cinnamon supplementation is helpful for diabetes or weight loss."[8] The studies on cinnamon and blood sugar are hard to read because it is often unclear which species or part of the plant was tested.[8]

The pooled numbers show why. A 2013 meta-analysis covered 10 trials in 543 people with type 2 diabetes. Doses ran from 120 mg (0.004 oz) to 6 g (0.21 oz) a day for 4 to 18 weeks. The pool found a difference in fasting glucose compared with control, with a wide confidence interval, meaning the true average could sit anywhere in a broad range. HbA1c did not change significantly. The authors said the high degree of heterogeneity, meaning how much the trials disagreed, may limit the ability to apply the results to patient care. They reported no conflicts of interest.[4]

A 2023 umbrella review, which pools earlier meta-analyses, covered 11 of them and found a smaller fasting glucose difference and an HbA1c change of 0.10 percentage points (about 1.1 mmol/mol). It pooled diabetes and polycystic ovary syndrome studies together, declared no funding and no conflicts.[12] One pool found no clear HbA1c change, the other 0.10 percentage points (about 1.1 mmol/mol).

A narrative review by NIH Office of Dietary Supplements staff looked at 11 trials. In 10 of them, participants kept taking their diabetes medicines during the cinnamon period. Seven trials used cassia, one used Ceylon and three did not say which species.[13] The authors advised people to keep following the diet, lifestyle and medicine advice of authoritative bodies until larger and more rigorous studies exist.[13]

Safety. Cassia cinnamon contains coumarin, which NCCIH says might cause or worsen liver disease.[8] Germany's Federal Institute for Risk Assessment sets a tolerable daily intake of 0.1 mg of coumarin per kg of body weight (about 0.045 mg per lb). A 60 kg (132 lb) adult reaches it with about 2 g (0.07 oz) of cassia a day, and a 15 kg (33 lb) child with about 0.5 g (0.02 oz). The institute warns that cinnamon supplements "may contain high levels of coumarin" and that the content varies by type and processing.[9] Trial doses went up to 6 g (0.21 oz) a day.[4] NCCIH also says Ceylon cinnamon in larger amounts during pregnancy is considered unsafe.[8]

What does the evidence say about chromium?

The trials disagree with each other almost completely, and the ADA does not recommend it for blood sugar.[3] Chromium is an essential trace mineral found in many foods. With too little of it, NCCIH notes, the body cannot use glucose efficiently.[8] The question is whether a chromium supplement does anything for people who are not short of it.

A 2020 meta-analysis of 28 trials in type 2 diabetes found a difference in fasting glucose and in HbA1c compared with control. The confidence interval for fasting glucose ran almost to zero, and the spread between trials was extreme: an I2 of 99.8%, which means the trials disagreed almost completely. We could not check who funded it.[5] NCCIH calls the chromium evidence weak and says the effects of taking it long term have not been well investigated.[8] The ADA puts chromium in the same sentence as cinnamon.[3]

Safety. Stomach pain and bloating are the common complaints. NCCIH also lists a few reports of kidney damage, liver damage, muscular problems and skin reactions after large doses.[8]

What about berberine?

Berberine has the largest trial pools of the four, and the biggest caveat. A 2022 meta-analysis of 37 trials in 3,048 people with type 2 diabetes found a difference in fasting glucose and in HbA1c compared with control over a few months. The trials tested berberine on its own or added to oral diabetes medicines. The authors declared no commercial or financial conflicts.[6] A 2019 pool of 28 trials in 2,313 people found a smaller difference in fasting glucose. It also found the effect became "unremarkable" past 90 days, above 2 g (0.07 oz) a day, and in people over 60. It was funded by a city science programme in Guangdong, China.[14]

NCCIH describes the limits of this evidence. Writing about a 2021 pool of 46 trials, it says the review was limited to mostly studies conducted among Chinese patients, there was wide variability in the effect on some outcomes, and some of the studies were of poor quality. The 2022 pool searched four Chinese databases alongside PubMed, Embase and Cochrane.[8] None of the pools reports heart, kidney or eye outcomes. They report glucose numbers over a few months.

Safety. This is where berberine differs from the others. NCCIH says it "should not be used during pregnancy or while breastfeeding, and it should not be given to infants". Exposure has been linked to a harmful buildup of bilirubin in infants that can cause brain damage.[8]

It may interact with some medicines, so people who take medicines should talk with their health care providers first.

Common side effects are nausea, diarrhoea, bloating and constipation. NCCIH reports that studies used 200 to 1,000 mg (0.007 to 0.035 oz) two to three times a day. That is a trial range, not a dose for you.[8] In the 2022 pool, adding berberine to oral diabetes medicines did not significantly change the rate of hypos (risk ratio 0.48, 95% CI 0.21 to 1.08).[6]

What does the evidence say about alpha-lipoic acid?

The changes in trials were below the level that matters clinically. A 2022 dose-response meta-analysis of 16 trials in 1,035 people with type 2 diabetes found small changes in HbA1c and fasting glucose compared with control. The authors then wrote that "the point estimates were below minimal clinically important difference thresholds for all outcomes". The work had no specific grant and the authors declared no conflict of interest.[7] NCCIH cites a 2019 review of 10 studies in 553 people in which alpha-lipoic acid was no better than placebo for blood sugar, cholesterol or triglycerides.[8]

The studied use is different. NCCIH says a 2022 review of 9 studies in 2,062 people found alpha-lipoic acid might help with pain from diabetic neuropathy, while another 2022 review found mixed results for symptoms.[8] That is a medical question for your team, not a supplement to pick off a shelf. NCCIH lists headache, heartburn, nausea and vomiting as the most common side effects, and cites a 2020 review of 71 studies that found supplementation safe.[8]

The four ingredients side by side

Each row sums up the pooled trials. A change in a trial average is not a promise for you.

Ingredient. Fasting glucose in pooled trials. HbA1c. Main safety point. Official position.
Cinnamon. A difference in two pools, very wide spread between trials.[4][12] No clear change in one pool, 0.10 percentage points (about 1.1 mmol/mol) in the other.[4][12] Coumarin in cassia and the liver.[9] ADA: not recommended. NCCIH: unclear.[3][8]
Chromium. A difference, I2 99.8%, trials disagreed.[5] A difference in the same pool.[5] Kidney and liver reports after large doses.[8] ADA: not recommended. NCCIH: weak.[3][8]
Berberine. A difference in two pools, mostly Chinese trials.[6][14] A difference in the same pool.[6] Not in pregnancy, breastfeeding or infants. Drug interactions.[8] NCCIH: weak, studies of mixed quality.[8]
Alpha-lipoic acid. Below the clinically important threshold.[7] Below the clinically important threshold.[7] Headache, heartburn, nausea.[8] NCCIH: no better than placebo for glucose.[8]

How to use any supplement safely with diabetes medicines

Start with your pharmacist. The NHS metformin page says some medicines, herbal remedies and supplements may not mix well with metformin, and asks you to tell your doctor or pharmacist about any supplement you take.[10] The gliclazide page carries the same line, and adds that gliclazide can cause low blood sugar on its own, with dizziness, nausea, hunger or tiredness as the signs.[10]

The ADA says hypo risk is highest in people who use insulin or insulin secretagogues (such as a sulfonylurea like gliclazide or glimepiride).[3] A supplement could add to the effect of those medicines and raise the risk of a low, so adding one is a step to plan with your team, not to test alone.

Low blood sugar usually means below 4 mmol/L (72 mg/dL) in the UK or below 70 mg/dL (3.9 mmol/L) in the US.[10][3] In the UK, the NHS says to call 999 if someone may have very low blood sugar and is not responding normally or is unconscious, and a glucagon injection is not available or you do not know how to use it, or they have not recovered within 10 minutes of a glucagon injection, or they have been drinking alcohol.[10] In the US, the ADA says to call 911 right away if someone is unconscious and glucagon is not available or no one knows how to use it.[3] Our guide to low blood sugar covers the signs in more detail.

Kidneys are the second thing to ask about. Kidney disease has been linked to some dietary supplements, and diabetes is the leading cause of kidney disease, and the NIH centre flags that link.[8] Diabetes UK says supplements may affect the way your diabetes medicines work and make complications such as kidney disease worse.[11]

Be wary of big claims. NCCIH passes on an FDA warning about products sold as a natural fix for diabetes or as a way to "replace your diabetes medicine". These products are marketed illegally. All are harmful if people use them in place of the medicines and care their doctor prescribes.[8] Diabetes UK says it does not recommend herbal remedies and supplements, because there is not enough evidence that they are safe and effective for people with diabetes.[11]

Five steps before you buy

  1. Write down every medicine you take and show the list to your pharmacist with the supplement label.[10]
  2. Check the label for the species. For cinnamon, look for Ceylon or cassia.[9][8]
  3. If you are pregnant, breastfeeding or planning a pregnancy, leave berberine and large amounts of cinnamon alone.[8]
  4. Agree with your team how you will check glucose during the first weeks, especially if you take insulin or gliclazide.[3][10]
  5. Judge it by your own HbA1c result at the next test, not by how you feel.[3]
Pro Tip

A label that does not name the species tells you nothing about the coumarin dose. Cassia, the common kind in the US and Canada, carries it. Ceylon may contain only a trace.[8][9]

Questions to ask your diabetes team

  • Do any of my medicines put me at risk of a hypo if I add a supplement?[10][3]
  • Is my kidney function good enough for this supplement?[8]
  • Can you refer me to a registered dietitian instead?[3]
  • If I try it, how will we know whether it did anything?[3]

Frequently asked questions

How much cassia cinnamon is too much?

For a 60 kg (132 lb) adult, about 2 g (0.07 oz) of cassia a day reaches the coumarin tolerable daily intake set by Germany's Federal Institute for Risk Assessment. For a 15 kg (33 lb) child it is about 0.5 g (0.02 oz). Trial doses went up to 6 g (0.21 oz) a day, and the institute says supplements may contain high levels of coumarin.[9][4] Diabetes UK puts the bigger question on its own website and answers it in four words: "the real answer is no". Herbal remedies should never replace the plan your diabetes team gave you.[11]

Is berberine safe in pregnancy?

No. NCCIH says berberine should not be used during pregnancy or while breastfeeding, and should not be given to infants. Exposure has been linked to a harmful buildup of bilirubin in infants, which can cause brain damage.[8]

Can I take a glucose support supplement with metformin or gliclazide?

Ask your pharmacist first. The NHS says some remedies and supplements may not mix well with metformin or gliclazide, and asks you to tell your doctor or pharmacist about any supplement you take.[10] Gliclazide can cause a hypo on its own, so adding a supplement needs a conversation first.[10]

Does any of these supplements have enough evidence?

None has enough. The ADA says there is insufficient evidence for routine use of herbal supplements and micronutrients to improve glycemia.[3] NCCIH calls the evidence for chromium, cinnamon and berberine weak, and says the findings differ too much to draw a clear conclusion.[8]

Are glucose support supplements approved by the FDA?

No. The FDA does not approve dietary supplements before they are sold, and does not approve structure/function claims such as a glucose support claim. The label must carry a disclaimer that says so.[1] In the UK such products are sold as food.[2]

Where to go next

The evidence for food, movement and your medicines is far stronger than the evidence for any glucose support capsule.[3]

Note: If you are pregnant, breastfeeding, or considering giving any supplement or herbal product to a child, consult your healthcare provider before making any changes to your diet, supplement routine, or prescribed medications.

Disclaimer: 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. Talk to your doctor before changing your diet, your activity or your medicines, and before starting any supplement.

Sources & References

  1. U.S. Food and Drug Administration (pages current as of 27 August 2026 and 1 October 2024). Questions and Answers on Dietary Supplements; Dietary Supplements. US regulator pages. fda.gov. Checked 25 October 2026.
  2. Food Standards Agency and Department of Health and Social Care (published 2 July 2018); Medicines and Healthcare products Regulatory Agency (updated 5 January 2024). Food supplements: guidance for businesses; Apply for a traditional herbal registration (THR). UK government guidance. gov.uk. Checked 25 October 2026.
  3. American Diabetes Association Professional Practice Committee for Diabetes (2026). 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2026. Diabetes Care. Committee disclosures are published separately by the ADA. pubmed.ncbi.nlm.nih.gov/41358898. American Diabetes Association. Hypoglycemia (Low Blood Glucose). diabetes.org. Checked 25 October 2026.
  4. Allen RW, Schwartzman E, Baker WL, Coleman CI, Phung OJ (2013). Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Annals of Family Medicine. The authors reported no conflicts of interest. No funding statement is given. pubmed.ncbi.nlm.nih.gov/24019277
  5. Asbaghi O, Fatemeh N, Mahnaz RK, et al. (2020). Effects of chromium supplementation on glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials. Pharmacological Research. Funding and conflicts of interest not stated in the PubMed record; full text not checked. pubmed.ncbi.nlm.nih.gov/32730903
  6. Xie W, Su F, Wang G, et al. (2022). Glucose-lowering effect of berberine on type 2 diabetes: A systematic review and meta-analysis. Frontiers in Pharmacology. The authors declared no commercial or financial relationships that could be a conflict of interest. Funding not stated in the PubMed record; full text not checked. pubmed.ncbi.nlm.nih.gov/36467075
  7. Jibril AT, Jayedi A, Shab-Bidar S (2022). Efficacy and safety of oral alpha-lipoic acid supplementation for type 2 diabetes management: a systematic review and dose-response meta-analysis of randomized trials. Endocrine Connections. The work received no specific grant from any funding agency. The authors declared no conflict of interest. pubmed.ncbi.nlm.nih.gov/36006850
  8. National Center for Complementary and Integrative Health (pages updated November 2023 and November 2024). Diabetes and Dietary Supplements: What You Need To Know; Cinnamon. US National Institutes of Health pages. nccih.nih.gov. Checked 25 October 2026.
  9. German Federal Institute for Risk Assessment (BfR) (27 September 2012). FAQ on coumarin in cinnamon and other foods. Government risk assessment body. bfr.bund.de. Checked 25 October 2026.
  10. NHS (pages last reviewed 6 August 2026 and 5 August 2026). Gliclazide; Metformin; Low blood sugar (hypoglycaemia) (page last reviewed 3 August 2023). nhs.uk. Checked 25 October 2026.
  11. Diabetes UK (page updated 9 July 2026). Herbal and food supplements. Charity page with no author or conflict of interest line. diabetes.org.uk. Checked 25 October 2026.
  12. Zarezadeh M, Musazadeh V, Foroumandi E, Keramati M, Ostadrahimi A, Mekary RA (2023). The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes or with polycystic ovary syndrome: an umbrella meta-analysis on interventional meta-analyses. Diabetology and Metabolic Syndrome. Funding: none. The authors declared no conflicts of interest. pubmed.ncbi.nlm.nih.gov/37316893
  13. Costello RB, Dwyer JT, Saldanha L, Bailey RL, Merkel J, Wambogo E (2016). Do Cinnamon Supplements Have a Role in Glycemic Control in Type 2 Diabetes? A Narrative Review. Journal of the Academy of Nutrition and Dietetics. The authors are staff of the NIH Office of Dietary Supplements. No funding or conflict of interest statement was found in the open author manuscript. pubmed.ncbi.nlm.nih.gov/27618575
  14. Liang Y, Xu X, Yin M, Zhang Y, Huang L, Chen R, Ni J (2019). Effects of berberine on blood glucose in patients with type 2 diabetes mellitus: a systematic literature review and a meta-analysis. Endocrine Journal. Supported by the Social science and technology development project of Dongguan, Guangdong, China. The authors declared no conflicts of interest. pubmed.ncbi.nlm.nih.gov/30393248
Back to blog