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BMJ Open. 2014 Jul 22;4(7):e005632. doi: 10.1136/bmjopen-2014-005632.

Tea consumption and risk of type 2 diabetes mellitus: a systematic review and meta-analysis update.

Author information

1
Department of Nutrition, Daping Hospital, The Third Military Medical University, Chongqing, People's Republic of China Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, People's Republic of China.
2
Social Medical Science Research Centre, National Research Institute for Family Planning, Beijing, People's Republic of China.
3
Department of Nutrition, Daping Hospital, The Third Military Medical University, Chongqing, People's Republic of China.
4
National Research Institute for Family Planning, Beijing, People's Republic of China.
5
Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, People's Republic of China.

Abstract

OBJECTIVE:

Tea has been suggested to decrease blood glucose levels and protect pancreatic β cells in diabetic mice. However, human epidemiological studies showed inconsistent results for the association between tea consumption and type 2 diabetes mellitus (T2DM) risk. The aim of this study was to conduct a meta-analysis to further explore the association between tea consumption and incidence of T2DM.

DESIGN:

Systematic review and meta-analysis.

METHODS:

We performed a systematic literature search up to 30 August 2013 in PubMed, EMBASE, Chinese Wanfang Database and CNKI database. Pooling relative risks (RRs) were estimated by random-effect models. Two kinds of subgroup analyses (according to sex and regions) were performed. Sensitive analyses were performed according to types of tea.

RESULTS:

Overall, no statistically significant relationship between tea consumption and risk of T2DM was found based on 12 eligible studies (pooling RR 0.99, 95% CI 0.95 to 1.03). Compared with the lowest/non-tea group, daily tea consumption (≥3 cups/day) was associated with a lower T2DM risk (RR 0.84, 95% CI 0.73 to 0.97). Subgroup analyses showed a difference between men and women. Overall, the RRs (95% CI) were 0.92 (0.84 to 1.00) for men, and 1.00 (0.96 to 1.05) for women, respectively. Tea consumption of ≥3 cups/day was associated with decreased T2DM risk in women (RR 0.84, 95% CI 0.71 to 1.00). Overall, the RRs (95% CIs) were 0.84 (0.71 to 1.00) for Asians, and 1.00 (0.97 to 1.04) for Americans and Europeans, respectively. No obvious change was found in sensitivity analyses.

CONCLUSIONS:

The results suggest that daily tea consumption (≥3 cups/day) is associated with a lower T2DM risk. However, further studies are needed to enrich related evidence, especially with regard to types of tea or sex.

KEYWORDS:

Epidemiology

PMID:
25052177
PMCID:
PMC4120344
DOI:
10.1136/bmjopen-2014-005632
[Indexed for MEDLINE]
Free PMC Article

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