Does Cinnamon Lower Blood Sugar? A Small Fasting Drop, No HbA1c Change, and No Ozempic Effect
Pooled trials found cinnamon trimmed fasting glucose but did not move HbA1c, the 3-month average. A 3 g dose nudged GLP-1 in 15 healthy people without changing blood sugar, so the "nature's Ozempic" label does not fit.
By Kymata Health Editorial Published Last checked
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Key takeaways
From 8 sources- A meta-analysis of 10 trials (543 people with type 2 diabetes) found fasting glucose fell 24.59 mg/dL with cinnamon, but HbA1c did not change significantly1.
- A Cochrane review of 10 trials (577 people) found no significant difference in HbA1c, insulin or post-meal glucose, and called the evidence insufficient2.
- In 15 healthy adults, 3 g of cinnamon raised the GLP-1 response after a meal but did not change blood glucose, fullness or stomach emptying3.
- A 4-week crossover trial in 18 adults with prediabetes found 4 g a day modestly lowered continuously monitored glucose, but that dose supplied more coumarin than the tolerable daily intake45.
- Coumarin in cassia cinnamon can harm the liver in sensitive people, and levels vary widely even within a single tree567.
What this article covers
1 evidence profileThe evidence, graded
Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.
Graded findings
2 rows- CGrade CFasting glucose and lipids in type 2 diabetesImproved Fasting glucose fell 24.6 mg/dL, total cholesterol 15.6, LDL 9.4 and triglycerides 29.6 mg/dL versus control, and HDL rose 1.7 mg/dL; HbA1c did not change.Cinnamon · Meta-analysis · n=543 · 2013 · PMID 24019277
- CGrade CHbA1c and glucose in diabetesNo effect No significant difference in HbA1c, insulin or post-meal glucose; the fasting glucose effect was inconclusive. Most trials had high or unclear risk of bias.Cinnamon · Systematic review · n=577 · 2012 · PMID 22972104
Where these trials agree: Cinnamon and blood sugar, counted row by row in the Consensus finder.
The short answer
Cinnamon may shave a little off fasting blood sugar, but the better-quality evidence has not shown a change in HbA1c, the measure doctors use to judge long-term control12. Both reviews we cite rate C on our scale because the trials were small, short and inconsistent12.
Claims that cinnamon is a natural GLP-1 drug rest on a single-meal study in 15 healthy people, in which blood glucose did not change3.
Fasting glucose and HbA1c: what pooled trials show
A 2013 meta-analysis pooled 10 randomized trials in 543 adults with type 2 diabetes, at doses from 120 mg to 6 g a day for 4 to 18 weeks1. Fasting glucose fell 24.59 mg/dL (95% CI −40.52 to −8.67), and total cholesterol, LDL and triglycerides also fell versus control1.
HbA1c did not change significantly (−0.16%, 95% CI −0.39% to 0.02%), and heterogeneity was high for every outcome except HDL, with I² from 66.5% to 94.72%1. The authors said the preferred dose and duration are unclear1.
The 2012 Cochrane review found 10 trials in 577 people with type 1 or type 2 diabetes, mostly using cassia at a mean 2 g a day for 4 to 16 weeks2. The fasting glucose effect was inconclusive, HbA1c, insulin and post-meal glucose did not differ, and risk of bias was high or unclear in all but 2 trials2. The review authors declared no conflicts2.
Is cinnamon "nature's Ozempic"?
In a Swedish crossover study, 15 healthy adults ate rice pudding with 0, 1 or 3 g of cinnamon3. The 3 g dose raised the GLP-1 response and lowered insulin, but glucose, GIP, ghrelin, fullness and the rate of stomach emptying did not change significantly with either dose; the insulin and GLP-1 changes were seen only with 3 g3.
The study measured stomach emptying and fullness, the effects people expect from a GLP-1 drug, and cinnamon changed neither3. A one-meal hormone change in healthy people is not evidence of drug-like weight loss.
For the same claim made about another supplement, see berberine as "nature's Ozempic".
The 2024 continuous glucose monitor trial
A UCLA crossover trial gave 18 adults with obesity and prediabetes (15 had usable monitor data from both phases) 4 g a day of Indonesian cinnamon (Cinnamomum burmannii) or placebo capsules for 4 weeks each, separated by a 2-week washout4. Average 24-hour glucose on a continuous monitor was lower on cinnamon, and glucose peaks were smaller (9.56 vs 11.73 mg/dL)4.
Glucose during an oral glucose tolerance test did not differ, insulin sensitivity by the Matsuda index did not change, and digestive symptoms were similar to placebo4. Participants followed a low-polyphenol, low-fibre diet throughout, so results may differ on a normal diet4.
The paper lists funding from UCLA's Center for Human Nutrition and no author conflicts of interest4. The McCormick Science Institute, a spice-industry research group, features the trial among its research reports, but the paper does not name it as a funder84. The authors noted they did not test liver safety and that the dose supplied 0.17 mg of coumarin per kg of body weight, above the tolerable daily intake of 0.1 mg/kg45.
Safety and who should avoid it
NCCIH says cinnamon is likely safe in the amounts used in food, and that larger amounts or long use are sometimes linked to stomach upset or allergic reactions7. The main concern with supplements is coumarin, which is concentrated in cassia cinnamon and can cause liver damage in a susceptible subgroup of people57.
European and German risk assessors set a tolerable daily intake of 0.1 mg of coumarin per kg of body weight5. In German retail testing, coumarin in cassia sticks from just two packages ranged from below detection to about 10,000 mg/kg, so a label cannot tell you how much you are getting6. By our arithmetic, a 70 kg adult would reach that limit with about 1.9 g of the cinnamon powder used in the UCLA trial45. Take extra care in these situations:
- Liver disease: NCCIH says prolonged use of cassia cinnamon could be a problem for sensitive people, such as those with liver disease7.
- People on insulin, sulfonylureas or other glucose-lowering medicines: pooled trials found cinnamon lowered fasting glucose1, so in theory it could add to these drugs and push blood sugar too low. No trial cited here tested the combination; check your glucose more often if you start it, and leave any dose changes to your clinician12.
- Pregnancy: NCCIH says food amounts appear safe but larger amounts of Ceylon cinnamon are considered unsafe in pregnancy7.
- Breastfeeding: little is known about larger amounts of either type7.
- People taking other medicines: NCCIH notes theoretical interactions with an anticancer medicine and with nicotine7.
- Anyone choosing a product: NCCIH says labels may not state the species or plant part used, which changes the chemistry7.
Quick answers
Common questions
4 answersHow much cinnamon was used in blood sugar trials?
Is Ceylon cinnamon safer than cassia?
Ceylon may contain only a trace of coumarin, while some cassia products contain high levels7.
Can cinnamon replace metformin or a GLP-1 drug?
Does cinnamon raise GLP-1?
In 15 healthy people, 3 g raised the GLP-1 response after one meal without changing glucose or fullness3.
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Where to buy Cinnamon
Products from brands we partner with that contain Cinnamon. Check the amount per serving against the doses studied, and the label for other ingredients.
Cinnamon products from partner brands
1 product Paid links · we earn a commission- Quick pickHerbsProNOW Foods Cinnamon Bark, 600 mg, 120 Veg Caps
2 veg capsules: 1,200 mg cinnamon bark (Cinnamomum verum and/or C. aromaticum)
$9.98one-timeChecked Oct 14, 2026
References
8 sources. Numbers in the text link here.
Sources cited in this article
8 sources- 1Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysisAnn Fam Med, 2013 · PMID 24019277
- 2Cinnamon for diabetes mellitusCochrane Database Syst Rev, 2012 · PMID 22972104
- 3Effects of 1 and 3 g cinnamon on gastric emptying, satiety, and postprandial blood glucose, insulin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1, and ghrelin concentrations in healthy subjectsAm J Clin Nutr, 2009 · PMID 19158209
- 4Effect of cinnamon spice on continuously monitored glycemic response in adults with prediabetes: a 4-week randomized controlled crossover trialAm J Clin Nutr, 2024 · PMID 38290699
- 5Toxicology and risk assessment of coumarin: focus on human dataMol Nutr Food Res, 2010 · PMID 20024932
- 6Quantification of flavoring constituents in cinnamon: high variation of coumarin in cassia bark from the German retail market and in authentic samples from IndonesiaJ Agric Food Chem, 2010 · PMID 20853872
- 7CinnamonNational Center for Complementary and Integrative Health (NCCIH), 2024
- 8Cinnamon Spice and Continuously Monitored Glycemic Response In Adults With Prediabetes: A 4-Week Randomized Controlled Crossover Trial (research summary)McCormick Science Institute, 2024
Cinnamon and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. Product links on this page are paid partner links.