Systematic review and meta-analysis of anti-hyperglycaemic effects of Pu-erh tea

Pu-erh tea was presumed to have anti-hyperglycaemic effects with limited evidence. This study uses meta-analysis to investigate anti-hyperglycaemic effect of Pu-erh tea. Five English databases and three Chinese ones were systematically searched up to July 31, 2018. Those databases were searched to identify studies containing keywords of 'Pu-erh', 'Pu'er', 'blood sugar', 'blood glucose' and 'hyperglycaemia'. RevMan 5 and Stata were then utilized to conduct meta-analysis. Systematic reviews collected two mice studies with sixteen records for meta-analysis. Meta-analysis results showed that Pu-erh tea has significant anti-hyperglycaemic effect on mice. Pooled weight mean difference of blood sugar on mice studies were 71 and 116 mg dL(-1) at 21st day and 28th day respectively. Meta-regression disclosed over a longer intervention period showed that Pu-erh tea can reduce fasting blood glucose. Secondly, a higher dose of Pu-erh is shown to lower fasting blood glucose more significantly.