The effect of curcumin supplementation on glycemic indices in adults: A meta-analysis of meta-analyses

Curcumin, an inherent polyphenolic compound, has the potential to influence glycemic indices. Nevertheless, the conclusions drawn from extant meta-analyses remain contentious. To determine the impact of curcumin supplementation on these indices, the current umbrella meta-analysis included existing systematic reviews and meta-analyses. A thorough systematic search was conducted using databases Embase, PubMed, WOS, Scopus, and the Cochrane Library to acquire peer-reviewed literature published before January 2024. The random-effects model was employed to conduct a meta-analysis. The present analysis incorporated a total of 22 meta-analytic studies. The findings of our study indicate that the administration of curcumin supplements leads to a significant decrease in fasting blood sugar levels (FBS) (ES: -1.63; 95 % CI: -2.36, -0.89, P<0.001; I2=88.4 %, P<0.001), homeostasis model assessment-estimated insulin resistance (HOMA-IR) (ES: -0.38; 95 % CI: -0.48, -0.28, P<0.001; I2=35.9 %, P=0.142), hemoglobin A1c (HbA1c) (ES: -0.44; 95 % CI: -0.67, -0.21, P<0.001; I2=65.0 %, P=0.014), and insulin (ES: -0.86; 95 % CI: -1.52, -0.21, P=0.010; I2=92.5 %, P<0.001). The results of this study suggest that the administration of curcumin supplements may be a beneficial intervention for enhancing glycemic indices.