Effects of turmeric (Curcuma longa) supplementation on glucose metabolism in diabetes mellitus and metabolic syndrome: An umbrella review and updated meta-analysis

Thanika Pathomwichaiwat; Peerawat Jinatongthai; Napattaoon Prommasut; Kanyarat Ampornwong; Wipharak Rattanavipanon; Surakit Nathisuwan; Ammarin Thakkinstian

doi:10.1371/journal.pone.0288997

Effects of turmeric (Curcuma longa) supplementation on glucose metabolism in diabetes mellitus and metabolic syndrome: An umbrella review and updated meta-analysis

PLoS One. 2023 Jul 20;18(7):e0288997. doi: 10.1371/journal.pone.0288997. eCollection 2023.

Authors

Thanika Pathomwichaiwat¹, Peerawat Jinatongthai², Napattaoon Prommasut³, Kanyarat Ampornwong³, Wipharak Rattanavipanon³, Surakit Nathisuwan³, Ammarin Thakkinstian⁴

Affiliations

¹ Faculty of Pharmacy, Department of Pharmaceutical Botany, Mahidol University, Bangkok, Thailand.
² Faculty of Pharmaceutical Sciences, Pharmacy Practice Division, Ubon Ratchathani University, Ubon Ratchathani, Thailand.
³ Faculty of Pharmacy, Department of Pharmacy, Mahidol University, Bangkok, Thailand.
⁴ Faculty of Medicine Ramathibodi Hospital, Department of Clinical Epidemiology and Biostatistics, Mahidol University, Bangkok, Thailand.

Abstract

Aims: This study aims to comprehensively review the existing evidence and conduct analysis of updated randomized controlled trials (RCTs) of turmeric (Curcuma longa, CL) and its related bioactive compounds on glycemic and metabolic parameters in patients with type 2 diabetes (T2DM), prediabetes, and metabolic syndrome (MetS) together with a sub-group analysis of different CL preparation forms.

Methods: An umbrella review (UR) and updated systematic reviews and meta-analyses (SRMAs) were conducted to evaluate the effects of CL compared with a placebo/standard treatment in adult T2DM, prediabetes, and MetS. The MEDLINE, Embase, The Cochrane Central Register of Control Trials, and Scopus databases were searched from inception to September 2022. The primary efficacy outcomes were hemoglobin A1C (HbA1C) and fasting blood glucose (FBG). The corrected covered area (CCA) was used to assess overlap. Mean differences were pooled across individual RCTs using a random-effects model. Subgroup and sensitivity analyses were performed for various CL preparation forms.

Results: Fourteen SRMAs of 61 individual RCTs were included in the UR. The updated SRMA included 28 studies. The CCA was 11.54%, indicating high overlap across SRMAs. The updated SRMA revealed significant reduction in FBG and HbA1C with CL supplementation, obtaining a mean difference (95% confidence interval [CI]) of -8.129 (-12.175, -4.084) mg/dL and -0.134 (-0.304, -0.037) %, respectively. FBG and HbA1C levels decreased with all CL preparation forms as did other metabolic parameters levels. The results of the sensitivity and subgroup analyses were consistent with those of the main analysis.

Conclusion: CL supplementation can significantly reduce FBG and HbA1C levels and other metabolic parameters in T2DM and mitigate related conditions, including prediabetes and MetS.

Trial registration: PROSPERO (CRD42016042131).

Copyright: © 2023 Pathomwichaiwat et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Review

MeSH terms

Adult
Blood Glucose / metabolism
Curcuma / metabolism
Diabetes Mellitus, Type 2* / drug therapy
Dietary Supplements
Glycated Hemoglobin
Humans
Meta-Analysis as Topic
Metabolic Syndrome* / drug therapy
Prediabetic State* / drug therapy
Randomized Controlled Trials as Topic
Systematic Reviews as Topic

Substances

Blood Glucose
Glycated Hemoglobin

Grants and funding

This study was supported by the National Research Council of Thailand (N42A640323). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.