The Effects of Curcumin on Glycemic Control and Lipid Profiles Among Patients with Metabolic Syndrome and Related Disorders: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: This systematic review and meta-analysis of randomized controlled trials (RCTs), were performed to determine the effects of curcumin intake on glycemic control and lipid profiles among patients with metabolic syndrome (MetS) and related disorders. Methods: We searched the following databases up until January 2018: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and evaluated for quality of the studies in accordance with the Cochrane risk of bias tool. Data were pooled using the inverse variance method and expressed as standardized mean difference (MDs) with 95% confidence intervals (95% CI). Results: Twenty-six trials with 1890 participants were included in the current meta-analysis. The findings demonstrated the significant association between curcumin intake and reduced fasting glucose levels (SMD -0.78; 95% CI, -1.20, -0.37; P<0.001), homeostasis model of assessment-estimated insulin resistance (SMD -0.91; 95% CI, -1.52, -0.31; P=0.003) and HbA1c (SMD -0.92; 95% CI, -1.37, -0.47; P<0.001). In addition, curcumin supplementation was significantly associated with triglyceride (SMD -1.21; 95 % CI, -1.78, -0.65; P<0.001) and total cholesterol reduction (SMD -0.73; 95 % CI, -1.32, -0.13; P=0.01). However, curcumin intake significantly increased insulin levels (SMD 0.92; 95% CI, 0.06, 1.78; P=0.036). We found no significant effect of curcumin supplementation on LDL-(SMD -0.52; 95% CI, -1.14, 0.11; P=0.10) and HDL-cholesterol levels (SMD 0.28; 95% CI, -0.22, 0.77; P=0.27). Conclusion: Overall, curcumin consumption was associated with a significant reduction in fasting glucose, HOMA-IR, HbA1c, triglycerides and total cholesterol levels among patients with MetS and related disorders, but did not affect LDL- and HDL-cholesterol levels.