A meta-analysis of 17 randomized controlled trials showed….
Weighted mean differences were calculated for net changes in glycemic measures by using fixed-effects or random-effects models. Pre-specified subgroup and sensitivity analyses to explore potential heterogeneity were conducted. Meta-regression analyses were conducted to investigate dose effects of green tea on fasting glucose and insulin concentrations.
Final results for the study were derived from seventeen trials comprising a total of 1133 subjects in the current meta-analysis. Green tea consumption was shown to notably decrease fasting glucose and hemoglobin A1c. Further stratified analyses showed that green tea significantly reduced fasting insulin concentrations (−1.16 μIU/mL; 95%CI: −1.91, −0.40 μIU/mL; P = 0.03).
Green tea consumption significantly reduced the fasting glucose and hemoglobin A1c (Hb A1c) concentrations by −0.09 mmol/L (95% CI: −0.15, −0.03 mmol/L; P < 0.01) and −0.30% (95% CI: −0.37, −0.22%; P < 0.01), respectively.
In conclusion, the researchers suggested that green tea had favorable effects on insulin resistance. Notable improvements during the study were: decreased fasting glucose and Hb A1c concentrations. A final subgroup analysis showed a significant reduction in fasting insulin concentrations in trials with high Jadad scores suggesting this study does hold a valid amount of accuracy.
Kia, Liu, Zhou Rui, et al. "Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials." American Journal of Clinical Nutrition . (2013): n. page. Web. 1 Jul. 2013. <http://ajcn.nutrition.org/content/early/2013/06/26/ajcn.112.052746.full.pdf html>.