Curcumin/Turmeric Supplementation on Glycemic Control in Adults With Prediabetes and Type 2 Diabetes: A Systematic Review and Dose–Response Meta‐Analysis

Curcumin and turmeric have demonstrated potential hypoglycemic properties in preclinical studies, but findings from human randomized controlled trials (RCTs) in prediabetes and type 2 diabetes (T2D) are inconsistent. PubMed, Scopus, and Web of Science ISI databases were comprehensively searched until August 2025 (25/08/2025) to find eligible RCTs. Overall effect sizes were estimated based on the random‐effect models and presented as weighted mean differences (WMD) with 95% confidence intervals (95% CI). All analyses were performed using version 17.0 (Stata Corp., College Station, TX, USA). Thirty‐four eligible RCTs (39 treatment arms) were included in this review. Curcumin/turmeric supplementation significantly reduced fasting blood glucose (FBG) (WMD = −10.15 mg/dL; 95% CI: −12.59, −7.72), hemoglobin A1c (HbA1c) (WMD = −0.32%; 95% CI: −0.43, −0.21), fasting insulin (WMD = −0.69 μU/ml; 95% CI: −1.27, −0.12), homeostatic model assessment of insulin resistance (HOMA‐IR) (WMD = −0.46; 95% CI: −0.60, −0.32), and oral glucose tolerance test (OGTT) (WMD = −11.53 mg/dL; 95% CI: −22.68, −0.44) compared to control groups. However, no significant alteration in homeostatic model assessment of β ‐cell function (HOMA‐B) levels was detected, followed by Curcumin or turmeric supplementation in comparison to the control groups. Subgroup analyses indicated that efficacy was modified by health status (T2D vs. prediabetes), dosage (≥ 1 g/day more effective), and formulation. This meta‐analysis revealed that curcumin/turmeric supplementation may improve glycemic control in individuals with prediabetes or T2D. Despite positive findings, significant heterogeneity across studies necessitates caution. Furthermore, future high‐quality RCTs are required to reach a firm conclusion.