Meta-analyses of the RCTs for ginger 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 |
|---|---|---|---|---|---|
| Garza et al. [168] (2024) | 45 RCTs (9 for ginger)/n = 3,050 | Ginger/Ginger oil /1.2–3 g/day | Ginger supplementationsignificantly reduced FBG and HbA1c, and improved insulin levels. | Supplementation with ginger significantly reduced FBG, HbA1c, and improved insulin levels in T2DM. | Significant heterogeneity between the studies in terms of products used and doses.Some studies had poor methodology, such as a lack of blinding of investigators and subjects, poor analytical methods, and a lack of control for confounding factors. Only four trials controlled for confounding, and only fourteen studies fully reported investigators’ blinding. Some studies had small sample sizes, and most studies were from the Middle East, so generalizability may be an issue. |
| Schumacher et al. [169] (2024) | 5 RCTs/n = 232 | Ginger/Fresh and dried ground to a powder/ 1.2–2 g/d | No significant effect of ginger supplementation on FBG or HbA1c. Mixed results for a reduction in fasting blood glucose in T2DM patients. | No conclusions can be made due to the limited number of trials and subjects included. | A small number of studies and subjects were included. Many studies included women only; thus, there may be a gender bias. Limitations in the ginger products included other methodical issues. |
| Ebrahimzadeh et al. [170] (2022) | 10 RCTs/not stated | Ginger/ginger oil | Ginger supplements significantly reduced FBG, HbA1c, and SBP and DBP. No significant effect on lipids. | Ginger reduced fasting blood glucose, HbA1c, and systolic and diastolic BP in patients with T2DM, but had no effect on lipid profiles. | Only studies in English were included. Most RCTs from Eastern countries, so generalizability is unknown.High heterogeneity as various doses and intervention times were used between studies. |
| Mohammad et al. [171] (2021) | 5 RCTs/n = 288 | Ginger supplements/1.6–3 g/d | Ginger supplementation significantly reduced hs-CRP, TNF-α, and IL-6 levels in patients with T2DM. | Ginger supplements reduced inflammatory parameters in patients with T2DM. | High risk of bias in some studies. A small number of studies and participants were included.Most studies from Middle Eastern countries are so generalizability is unknown. Additionally, no subgroup analyses were performed.High heterogeneity in products used, doses, and intervention times between studies. |
| Huang et al. [172] (2019) | 8 RCTs/n = 454 | Ginger supplements/ 1.6–4 g/d | No significant effect on FBG. However, a significant reduction in HbA1c. | Ginger supplementation had no significant effect on FBG but may reduce HbA1c over time in T2DM patients. | A small number of studies and participants were included.Significant heterogeneity in follow-up time period (8 to 12 weeks) and ginger products and doses. |
| Zhu et al. [173] (2018) | 10 RCTs/n = 490 | Ginger/various | Significant improvements in glycemic control and insulin sensitivity in T2DM. Reduced HbA1c and FBG. Improvements in lipid parameters were also observed. | Ginger improved glycemic control, insulin sensitivity, and lipid profiles in T2DM patients. | The study was limited in that it only included RCTs published in English or Chinese, and thus, the results may be biased. A limited number of studies and subjects may restrict the validity and generalizability. Brief treatment duration in most studies. Limited ability to detect statistically significant changes in BMI. |
CRP: C-reactive protein; DBP: diastolic blood pressure; FBG: fasting blood glucose; HbA1c: glycated hemoglobin; RCTs: randomized controlled trials; SBP: systolic blood pressure; T2DM: type 2 diabetes mellitus.
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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