Tea consumption and risk of type 2 diabetes: a meta-analysis of cohort studies

J Gen Intern Med. 2009 May;24(5):557-62. doi: 10.1007/s11606-009-0929-5. Epub 2009 Mar 24.

Abstract

Background: Tea consumption has been extensively studied in relation to various diseases, several epidemiologic studies have been performed to investigate the association of tea consumption with type 2 diabetes; however, the results of these studies were not entirely consistent.

Objective: To conduct a meta-analysis of studies that assessed the association of tea consumption and the risk of type 2 diabetes.

Research design and methods: We performed a systematic literature search through November 2008 in PUBMED, MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews. The search was limited to English-language studies. Studies were excluded if they were type 1 diabetes, animal studies. Nine cohort studies were identified by two authors, and summary relative risks (RRs) were calculated using a random-effects model.

Results: We identified nine cohort studies, including 324,141 participants and 11,400 incident cases of type 2 diabetes with follow-up ranging from 5 to 18 years. The summary adjusted RR did not show that tea consumption was associated with a reduced type 2 diabetes risk (RR, 0.96; 95% confidence interval (CI), 0.92-1.01). Evidence from the results of our stratified analyses revealed that tea consumption > or =4 cups per day (RR, 0.8; 95% CI, 0.7-0.93) might play a role in the prevention of type 2 diabetes. However, no statistically significant association was observed for sex and the follow-up durations stratified between tea consumption and type 2 diabetes.

Conclusions: This meta-analysis indicates that tea consumption > or =4 cups per day may lower the risk of type 2 diabetes.

Publication types

  • Comparative Study
  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Diabetes Mellitus, Type 2 / epidemiology*
  • Diabetes Mellitus, Type 2 / prevention & control*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Risk Factors
  • Tea*

Substances

  • Tea