Comparative effectiveness of turmeric and curcumin formulations on glycemic, lipid, and inflammatory markers in people with prediabetes: A systematic review and network meta-analysis.
TL;DR
Overall certainty of evidence was low due to heterogeneity and short trial durations, and variability among combination formulations, in prediabetes, but formulation-specific metabolic effects were observed.
Abstract
Prediabetes is a growing global health concern associated with higher risk of diabetes and cardiovascular disease. Curcumin has been studied for glycemic, lipid, and inflammatory effects, but comparative data across formulations remain limited. This network meta-analysis (NMA) evaluated turmeric and curcumin formulations in adults with prediabetes. Seven databases were searched for randomized controlled trials (RCTs) comparing turmeric/curcumin formulations with placebo. Primary outcomes included glycemic, lipid, and inflammatory markers. Two reviewers independently extracted data and assessed risk of bias. NMAs with surface under the cumulative ranking curve (SUCRA) were performed. Twenty-four RCTs (25 publications, 1,952 participants; mean baseline fasting blood sugar (FBS): 110.3mg/dL) evaluating eight curcumin-based formulations were included. Turmeric extract combined with other compounds (EC) and turmeric extract (E) were associated with significant reductions in FBS with WMD -10.73 (95%CI: -14.22, -7.25;SUCRA 92.2%), and -10.57 (95%CI: -14.35, -6.79;91.5%;SUCRA 91.5%), respectively. E was associated with a significant reduction in HbA1c, while EC was associated with lower HOMA-IR with MWD -0.73 (95%CI: -1.41, -0.05; SUCRA 79.8%). Whole turmeric with other compounds (WC) was associated with a significant reduction in LDL-C (WMD: -37.19, 95%CI: -56.97, -17.42; SUCRA: 97.3%). E was associated with a lower risk of incident type 2 diabetes (RR= 0.05; 95%CI:0.00,0.78), although this estimate was based on low-certainty of evidence. No significant effects were observed for inflammatory markers. Overall certainty of evidence was low due to heterogeneity and short trial durations, and variability among combination formulations. In prediabetes, formulation-specific metabolic effects were observed. However, given the low certainty of evidence, these findings should be interpreted cautiously and confirmed in larger, longer-term trials before clinical recommendation can be made.