Supplements · Diets · Metabolic & Cardiometabolic
cinnamon decreases fasting glucose
In plain terms: Does cinnamon meaningfully lower blood sugar?
Cinnamon can blunt acute postprandial glucose in small trials but reviews find no reliable HbA1c/fasting benefit — the general "lowers glucose" claim is contested and weak in healthy people.
📅 Last reviewed: 2026-07-14 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
Cinnamon's glycemic effect is real-but-fragile and heterogeneous; a 2025 GRADE MA finds significant-but-controversial effects while the 2012 Cochrane review found insufficient evidence. Coumarin (cassia) toxicity caps dose — a flavor lever, not a defensible glucose claim.
The evidence (15)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Allen RW, Schwartzman E, Baker WL, Coleman CI, Phung OJ 2013 · Ann Fam Med | meta-analysis | supports | moderate | Updated RCT meta-analysis: cinnamon significantly lowered fasting glucose and lipids |
| Beejmohun V, Peytavy-Izard M, Mignon C, Muscente-Paque D, Deplanque X, Ripoll C, Chapal N 2014 · BMC Complement Altern Med | RCT | tested-null | low | Ceylon cinnamon extract acutely reduced postprandial glucose via alpha-amylase inhibition in healthy volunteers; single small acute trial. |
| Jafari A, Mardani H, Faghfouri AH, AhmadianMoghaddam M, Musazadeh V, Alaghi A 2025 · (SR/MA) | meta-analysis | supports | low | GRADE MA: significant but heterogeneous/controversial glycemic effects |
| Zelicha H, Yang J, Henning SM, Huang J, Lee RP, Thames G, Livingston EH, Heber D, Li Z 2024 · Am J Clin Nutr | RCT | supports | moderate | 4-wk CGM crossover prediabetes; cinnamon spice lowered continuous glycemic response |
| Romeo GR, Lee J, Mulla CM, Noh Y, Holden C, Lee BC 2020 · J Endocr Soc | RCT | mixed | moderate | Prediabetes RCT: cinnamon lowered fasting glucose and blunted excursions vs placebo |
| Sabzevari Rad R, Omidi H, Alipour M 2025 · J Int Soc Sports Nutr | RCT | mixed | low | In overweight/obese soldiers, 8 weeks of cinnamon supplementation (500mg capsules, 3x/day) combined with or without Tabata training significantly decreased fasting blood sugar, insulin, and HOMA-IR across all intervention groups ( |
| Ranasinghe P, Jayawardana R, Galappaththy P, Constantine GR, de Vas Gunawardana N, Katulanda P 2012 · Diabet Med | meta-analysis | mixed | moderate | SR/meta of Cinnamomum zeylanicum: some glycemic signal but evidence limited and inconsistent. |
| Leach MJ, Kumar S 2012 · Cochrane Database Syst Rev | meta-analysis | tested-null | high | Cochrane SR, 10 RCTs / 577 people with type 1 or 2 diabetes, cinnamon (mainly C. cassia) mean 2 g/day for 4-16 weeks; 'Risk of bias was high or unclear in all but two trials'. On fasting glucose: 'The effect of cinnamon on fasting blood glucose level was inconclusive' - no pooled estimate in the abstract, so null vs heterogeneous is cannot-tell; HbA1c, insulin and postprandial glucose showed no significant difference. Authors: 'insufficient evidence to support the use of cinnamon'. |
| Ranasinghe P, Galappatthy P, Constantine GR, Jayawardena R, Weeratunga HD, Premakumara S, Katulanda P 2025 · Diabetes Metab Syndr | RCT | supports | moderate | Ceylon cinnamon extract RCT in T2DM; antihyperglycemic effect on glycemia |
| Moridpour AH, Kavyani Z, Khosravi S, Farmani E, Daneshvar M, Musazadeh V, Faghfouri AH 2024 · Phytother Res | meta-analysis | supports | moderate | 24-RCT FBS SMD -1.32 but high heterogeneity, cassia-dominated low-quality |
| Deyno S, Eneyew K, Seyfe S, Tuyiringire N, Peter EL, Muluye RA, Tolo CU, Ogwang PE 2019 · Diabetes Res Clin Pract | meta-analysis | supports | moderate | Meta-analysis+meta-regression T2DM/prediabetes: cinnamon reduced fasting glucose |
| Lira Neto JCG, Damasceno MMC, Ciol MA, de Freitas RWJF, de Araújo MFM, Teixeira CRS, Carvalho GCN, Lisboa KWSC, Marques RLL, Alencar AMPG, Zanetti ML 2022 · J Am Nutr Assoc | RCT | supports | moderate | 3g/day x90d in 160 T2DM: modest 0.55 mmol/L fasting glucose drop vs placebo |
| Muthukuda D, de Silva CK, Ajanthan S, Wijesinghe N, Dahanayaka A, Pathmeswaran A 2025 · PLoS One | RCT | supports | moderate | C. zeylanicum extract RCT; glucose secondary endpoint, effect modest |
| de Moura SL, Gomes BGR, Guilarducci MJ, Coelho OGL, Guimarães NS, Gomes JMG 2025 · Nutr Rev | meta-analysis | mixed | moderate | SR/MA cinnamon on metabolic biomarkers T2DM; glucose effect modest, biomarker-dependent |
| Mandal A, Sharma S, Rani R, Ranjan S, Kant R, Mirza A 2021 · Cureus | meta-analysis | tested-null | low | MA of 8 small RCTs of cassia bark powder 1-2 g/day for 40-90 days in T2D (n=510). Fasting glucose (7 trials, 401 patients): MD -12.60 mg/dL (95% CI -27.57 to 2.37; P=0.1) - underpowered trend toward lower FBG, interval includes zero. HbA1c (7 trials, 490) MD 0.01% (-0.11 to 0.13). Heterogeneity I2 0-84% across outcomes; no funnel plot drawn. Authors conclude powdered cassia 'doesn't decrease fasting blood glucose'; point estimate favours the claim, so tested-null, not contradicts. |
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.