Effect of ginger (Zingiber officinale) on blood glucose and lipid concentrations in diabetic and hyperlipidemic subjects: A meta-analysis of randomized controlled trials

•Ginger can exert beneficial effects on some lipid markers.•Ginger promotes insulin sensitivity and signaling through different mechanisms.•Beneficial effects of ginger are observable in hyperlipidemic and diabetic subjects. The aim of our study was to assess the effect of ginger (Zingiber officinale) on blood glucose and lipid concentration in subjects with diabetes or hyperlipidemia. The literature search was conducted in PubMed and Scopus up to 30 October 2016. A total of nine randomized controlled trials were included in the meta-analysis. Weighted mean difference (WMD) and its 95% confidence interval were calculated for net changes in blood glucose (fasting blood-glucose [FBG]) and lipid concentrations (total cholesterol [TC], triglyceride [TG], low-density lipoprotein cholesterol [LDL-C], high density lipoprotein cholesterol [HDL-C]). Subgroup analyses were performed by clinical condition (hyperlipidemia and T2DM) and quality assessment (high and low quality). Compared to the controls, ginger intake significantly reduced the concentrations of TG (WMD, −8.84; 95% CI: −11.95 to −5.73), TC (WMD, −4.42; 95% CI: −8.70 to −0.13), HDL-C (WMD, 2.87; 95% CI: 0.88–4.86) and FBG (WMD=−14.93; 95% CI: −19.83 to −10.04). Subgroup analyses by clinical condition of hyperlipidemia and high quality studies showed consistent results with the overall analysis, whereas, the subgroup analysis by clinical condition of diabetes showed a significant difference in the mean change of TG and FBG levels. Moreover, the high risk studies showed a significant change in the mean of FBG. Examining the funnel plot, suggests no publication bias. Ginger supplementation (tablet, capsules, powder or rhizomes) significantly reduced FBG, TG and TG and significantly increased HDL-C. But the changes were related to the clinical condition. More clinical trials evaluating the effects of ginger are warranted.