Objective Pu-erh tea was presumed to have anti-hyperglycemic effects via inhibition on alpha-amylase and alpha-glucosidase. However, no integerated literatures were published to substantiate such presumption. Methods Current study adopted systemic review method to validate inhibitory effects on alpha amylase and alpha-glucosidase. Five English databases (PubMed, EBSCO, SCOPUS, Cochrane Library, Web of Science) and three Chinese ones (Airti Library, CNKI Library, and Google Scholar) were searched up to 22 March 2018 for eligible literatures, using keywords of Pu-erh, Pu’er, alpha-amylase or alpha-glucosidase. Results Six studies exploring inhibitory effects on alpha-glucosidase and seven on alpha-amylase were included for systemic review. Though results showed pu-erh tea has significant inhibitory effects on alpha-amylase and alpha-glucosidase, high heterogeneity was detected among studies included. Conclusions High heterogeneity may be due to complex alterations of chemicals under different degrees of fermentation. More future studies are required to further identify principal bioactive component(s) at work.

Summary 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.