Meta-analyses of the RCTs for turmeric/curcumin supplements and their effects on glycemic indices, inflammatory markers, and oxidative stress in T2DM patients.
| Reference | Number of studies/patients included | Intervention/dosage form/dose | T2DM outcomes | Conclusions | Study limitations |
|---|---|---|---|---|---|
| Kehinde et al. [150] (2025) | 104 RCTs/n > 6,500 | Turmeric/curcumin/various dosage forms and doses | Significantly reduced FBG, HbA1c, TG, and LDL-C. Increased HDL-C and TAC. In addition, inflammation was reduced, including CRP and IL-6, in T2DM patients. | Supplementation of T2DM patients with turmeric/curcumin improved glucose regulation and lipid metabolism and reduced inflammation and oxidative stress. | Some studies had small sample sizes. Most studies from the Middle East or India, so generalizability may be an issue.Significant heterogeneity among the studies in terms of products used, disease severity, and methodological quality. Some studies had issues with randomization, nonadherence to planned interventions, and missing outcomes. |
| Bahari et al. [151] (2025) | 28 RCTs/not stated | Turmeric/curcumin/various dosage forms and doses | Significantlyreduced markers of inflammation and oxidative stress, such as CRP, TNF-α, IL-6, and MDA. Increased glutathione and TAC. Higher doses (≥ 1 g/day) and unformulated curcumin showed better effects. | Turmeric/curcumin supplementation reduces inflammatory and oxidative stress biomarkers in prediabetes and T2DM patients. Favorable safety profile. | Studies included were relatively small in sample size, short duration, and geographically concentrated.High heterogeneity, signs of publication bias, and the reliance on surrogate biomarkers rather than clinical endpoints. |
| Marton et al. [152], (2021) | 16 RCTs/n = 1,309 | Turmeric/curcumin/various dosage forms and doses (80 –2,100 mg/day) | Significantly reduced lipid peroxidation, FBG levels, HbA1C, TG, TC, LDL-C, CRP, systolic, and DBP. Significantly increased HDL-C levels and serum antioxidant capacity were also found. | Turmeric/curcumin supplementation improved FBG, HbA1c, insulin resistance, lipid profiles, and reduced inflammationbiomarkers in T2DM patients. | A limited number of databases and RCTs were included.Significant heterogeneity in intervention duration, intervention times, and dosage. Most studies were from the Middle East or Southeast Asia; thus, this potentially induces bias, and the generalizability may be poor. |
| Qiu et al. [153] (2023) | 13 RCTs/n = 785 | Curcumin/various | Supplementation reduced waist circumference, FBG, TC, and BP, and inflammatory markers, including TNF- and CRP. MDA was also reduced, suggesting a decrease in oxidative stress. No significant results were seen for total triglycerides, IL-6, or hs-CRP. | Curcumin significantly reduced markers associated with T2DM and metabolic syndrome, including inflammation and oxidative stress. | Twelve of the 13 RCTs were from Asian and Middle Eastern countries; the analysis may not be generalizable to other populations.A small number of trials and patients included in the analysis was low. Many studies were of very low to moderate quality.High bias in some of the studies due to only male participants or female participants. Some RCTs used combination curcumin studies (including piperine or alkaloids) to enhance bioavailability, but other ingredients may have caused bias in the analysis. The curcumin dose was not analyzed. |
| Macena et al. [154] (2022) | 17 RCTs included/5 RCTs for turmeric/curcumin n = 745 | Turmeric/curcumin/various products/80–1,500 mg/day | Significant reductions in HbA1c, proteinuria, and MDA in T2DM patients. Also increased in the GFR.Sub-group analyses indicated a reduction in CRP concentrations in the group receiving polyphenols and soy protein. No effects on FBG. | Statistically significant but clinically modest effects of turmeric/curcumin and polyphenol consumption for reductions in HbA1c, proteinuria, GFR, CRP, and MDA. | A limited number of clinical trials were included. Difficult to interpret due to specific polyphenols having different overall effects.Significant heterogeneity in the interventions, intervention duration, intervention times, and dosage. Most studies had a high risk of bias and poor reporting of methodology. |
CRP: C-reactive protein; DBP: diastolic blood pressure; FBG: fasting blood glucose; GFR: glomerular filtration rate; HbA1c: glycated hemoglobin; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; MDA: malondialdehyde; RCTs: randomized controlled trials; T2DM: type 2 diabetes mellitus; TAC: total antioxidant capacity; TC: total cholesterol; TG: triglycerides.
The supplementary material for this article is available at: https://www.explorationpub.com/uploads/Article/file/101474_sup_1.pdf.
SMW: Investigation, Writing—original draft, Writing—review & editing. TOL: Validation, Writing—review & editing. BAA: Investigation, Validation, Writing—original draft, Writing—review & editing. GPA: Investigation, Writing—review & editing. GBM: Conceptualization, Investigation, Writing—original draft, Writing—review & editing. All authors read and approved the submitted version.
The authors declare that they have no conflicts of interest.
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All information and data in this review are in the public domain. The primary data for this systematic review were sourced online from databases listed in the methods. Referenced articles are accessible on Cochrane Library, PubMed Central/Medline, Embase, Google Scholar, and the Scopus electronic databases. Additional supporting data are available from the corresponding author upon request.
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