Diabetes Metab J.  2017 Aug;41(4):251-262. 10.4093/dmj.2017.41.4.251.

The Effectiveness of Green Tea or Green Tea Extract on Insulin Resistance and Glycemic Control in Type 2 Diabetes Mellitus: A Meta-Analysis

• Yu J
• Song P
• Perry R
• Penfold C
• Cooper AR

• KMID: 2392465
• DOI: http://doi.org/10.4093/dmj.2017.41.4.251

Abstract

Green tea or green tea extract (GT/GTE) has been demonstrated to reduce insulin resistance and improve glycemic control. However, evidence for this health beneficial effect is inconsistent. This systematic review evaluated the effect of GT/GTE on insulin resistance and glycemic control in people with pre-diabetes/type 2 diabetes mellitus (T2DM). Ovid MEDLINE, Embase, AMED, Web of Science, and the Cochrane Library were searched up to April 2017 for randomised controlled trials of participants with pre-diabetes or T2DM, where the intervention was GT/GTE. Meta-analysis was performed to assess the standardised mean difference (SMD) in biomarkers of insulin resistance and glycemic control between GT/GTE and placebo groups. Six studies (n=382) were pooled into random-effects meta-analysis. Overall, no differences were found between GT/GTE and the placebo for glycosylated hemoglobin (HbA1c: SMD, −0.32; 95% confidence interval [CI], −0.86 to 0.23), homeostatic model assessment for insulin resistance (HOMA-IR: SMD, 0.10; 95% CI, −0.17 to 0.38), fasting insulin (SMD, −0.25; 95% CI, −0.64 to 0.15), and fasting glucose (SMD, −0.10; 95% CI, −0.50 to 0.30). No evidence support the consumption of GT/GTE could reduce the levels of HbA1c, HOMA-IR, fasting insulin, or fasting glucose in people with pre-diabetes/T2DM. However, the studies included were small and of varying quality.

Keyword

Diabetes mellitus, type 2; Glycemic control; Green tea; Insulin resistance; Meta-analysis

MeSH Terms

Biomarkers
Diabetes Mellitus
Diabetes Mellitus, Type 2*
Fasting
Glucose
Hemoglobin A, Glycosylated
Insulin Resistance*
Insulin*
Tea*
Biomarkers
Glucose
Insulin
Tea

Figure

• 

  Fig. 1 Flow-chart of study selection and exclusion in details.Adapted from www.mdpi.com/link.

• 

  Fig. 2 Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

• 

  Fig. 3 Meta-analysis results for each assessed outcome. (A) Comparison between decaffeinated green tea extract and placebo, outcome: glycosylated hemoglobin (HbA1c, %). (B) Comparison between decaffeinated green tea extract and green tea extract, outcome: fasting glucose. (C) Comparison between decaffeinated green tea extract and green tea extract, outcome: fasting insulin. (D) Comparison between decaffeinated green tea extract and green tea extract versus placebo, outcome: homeostatic model assessment for insulin resistance (HOMA-IR). SD, standard deviation; IV, independent variable; CI, confidence interval.

Reference

1. World Health Organization. Obesity: preventing and managing the global epidemic. Geneva: World Health Organization;2000.

2. Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature. 2006; 444:840–846. PMID: 17167471.

3. World Health Organization. Global status report on noncommunicable diseases 2014. Geneva: World Health Organization;2014.

4. American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010; 33(Suppl 1):S62–S69. PMID: 20042775.

5. DeFronzo RA. Insulin resistance, lipotoxicity, type 2 diabetes and atherosclerosis: the missing links. The Claude Bernard Lecture 2009. Diabetologia. 2010; 53:1270–1287. PMID: 20361178.

6. Ovalle F, Azziz R. Insulin resistance, polycystic ovary syndrome, and type 2 diabetes mellitus. Fertil Steril. 2002; 77:1095–1105. PMID: 12057712.

7. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. Obstet Gynecol Surv. 2003; 58:182–183.

8. Huxley R, Lee CM, Barzi F, Timmermeister L, Czernichow S, Perkovic V, Grobbee DE, Batty D, Woodward M. Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis. Arch Intern Med. 2009; 169:2053–2063. PMID: 20008687.

9. Cabrera C, Artacho R, Gimenez R. Beneficial effects of green tea: a review. J Am Coll Nutr. 2006; 25:79–99. PMID: 16582024.

10. Bose M, Lambert JD, Ju J, Reuhl KR, Shapses SA, Yang CS. The major green tea polyphenol, (-)-epigallocatechin-3-gallate, inhibits obesity, metabolic syndrome, and fatty liver disease in high-fat-fed mice. J Nutr. 2008; 138:1677–1683. PMID: 18716169.

11. Ortsater H, Grankvist N, Wolfram S, Kuehn N, Sjoholm A. Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice. Nutr Metab (Lond). 2012; 9:11. PMID: 22333133.

12. Tsuneki H, Murata S, Anzawa Y, Soeda Y, Tokai E, Wada T, Kimura I, Yanagisawa M, Sakurai T, Sasaoka T. Age-related insulin resistance in hypothalamus and peripheral tissues of orexin knockout mice. Diabetologia. 2008; 51:657–667. PMID: 18256806.

13. Oba S, Nagata C, Nakamura K, Fujii K, Kawachi T, Takatsuka N, Shimizu H. Consumption of coffee, green tea, oolong tea, black tea, chocolate snacks and the caffeine content in relation to risk of diabetes in Japanese men and women. Br J Nutr. 2010; 103:453–459. PMID: 19818197.

14. Toolsee NA, Aruoma OI, Gunness TK, Kowlessur S, Dambala V, Murad F, Googoolye K, Daus D, Indelicato J, Rondeau P, Bourdon E, Bahorun T. Effectiveness of green tea in a randomized human cohort: relevance to diabetes and its complications. Biomed Res Int. 2013; 2013:412379. PMID: 24102055.

15. Basu A, Du M, Sanchez K, Leyva MJ, Betts NM, Blevins S, Wu M, Aston CE, Lyons TJ. Green tea minimally affects biomarkers of inflammation in obese subjects with metabolic syndrome. Nutrition. 2011; 27:206–213. PMID: 20605696.

16. Fukino Y, Ikeda A, Maruyama K, Aoki N, Okubo T, Iso H. Randomized controlled trial for an effect of green tea-extract powder supplementation on glucose abnormalities. Eur J Clin Nutr. 2008; 62:953–960. PMID: 17554248.

17. Hsu CH, Liao YL, Lin SC, Tsai TH, Huang CJ, Chou P. Does supplementation with green tea extract improve insulin resistance in obese type 2 diabetics? A randomized, double-blind, and placebo-controlled clinical trial. Altern Med Rev. 2011; 16:157–163. PMID: 21649457.

18. Brown AL, Lane J, Coverly J, Stocks J, Jackson S, Stephen A, Bluck L, Coward A, Hendrickx H. Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial. Br J Nutr. 2009; 101:886–894. PMID: 18710606.

19. Liu CY, Huang CJ, Huang LH, Chen IJ, Chiu JP, Hsu CH. Effects of green tea extract on insulin resistance and glucagon-like peptide 1 in patients with type 2 diabetes and lipid abnormalities: a randomized, double-blinded, and placebo-controlled trial. PLoS One. 2014; 9:e91163. PMID: 24614112.

20. Liu K, Zhou R, Wang B, Chen K, Shi LY, Zhu JD, Mi MT. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. Am J Clin Nutr. 2013; 98:340–348. PMID: 23803878.

21. Wang X, Tian J, Jiang J, Li L, Ying X, Tian H, Nie M. Effects of green tea or green tea extract on insulin sensitivity and glycaemic control in populations at risk of type 2 diabetes mellitus: a systematic review and meta-analysis of randomised controlled trials. J Hum Nutr Diet. 2014; 27:501–512. PMID: 24206044.

22. Schulz KF, Altman DG, Moher D. CONSORT Group. CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials. BMC Med. 2010; 8:18. PMID: 20334633.

23. Higgins JP, Green S. Cochrane handbook for systematic reviews of interventions. Chichester: John Wiley & Sons;2011.

24. Huyen VT, Phan DV, Thang P, Hoa NK, Ostenson CG. Antidiabetic effect of Gynostemma pentaphyllum tea in randomly assigned type 2 diabetic patients. Horm Metab Res. 2010; 42:353–357. PMID: 20213586.

25. Huyen VT, Phan DV, Thang P, Hoa NK, Ostenson CG. Gynostemma pentaphyllum tea improves insulin sensitivity in type 2 diabetic patients. J Nutr Metab. 2013; 2013:765383. PMID: 23431428.

26. Lasaite L, Spadiene A, Savickiene N, Skesters A, Silova A. The effect of Ginkgo biloba and Camellia sinensis extracts on psychological state and glycemic control in patients with type 2 diabetes mellitus. Nat Prod Commun. 2014; 9:1345–1350. PMID: 25918808.

27. Mirzaei K, Hossein-Nezhad A, Karimi M, Hosseinzadeh-Attar MJ, Jafari N, Najmafshar A, Larijani B. Effect of green tea extract on bone turnover markers in type 2 diabetic patients: a double-blind, placebo-controlled clinical trial study. Daru. 2010; 17(Suppl 1):38–44.

28. Mousavi A, Vafa M, Neyestani T, Khamseh M, Hoseini F. The effects of green tea consumption on metabolic and anthropometric indices in patients with type 2 diabetes. J Res Med Sci. 2013; 18:1080–1086. PMID: 24523800.

29. Mozaffari-Khosravi H, Ahadi Z, Fallah Tafti M. The effect of green tea versus sour tea on insulin resistance, lipids profiles and oxidative stress in patients with type 2 diabetes mellitus: a randomized clinical trial. Iran J Med Sci. 2014; 39:424–432. PMID: 25242840.

30. Nagao T, Meguro S, Hase T, Otsuka K, Komikado M, Tokimitsu I, Yamamoto T, Yamamoto K. A catechin-rich beverage improves obesity and blood glucose control in patients with type 2 diabetes. Obesity (Silver Spring). 2009; 17:310–317. PMID: 19008868.

31. Ryu OH, Lee J, Lee KW, Kim HY, Seo JA, Kim SG, Kim NH, Baik SH, Choi DS, Choi KM. Effects of green tea consumption on inflammation, insulin resistance and pulse wave velocity in type 2 diabetes patients. Diabetes Res Clin Pract. 2006; 71:356–358. PMID: 16169629.

32. Mackenzie T, Leary L, Brooks WB. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Metabolism. 2007; 56:1340–1344. PMID: 17884442.

33. Fenercioglu AK, Saler T, Genc E, Sabuncu H, Altuntas Y. The effects of polyphenol-containing antioxidants on oxidative stress and lipid peroxidation in type 2 diabetes mellitus without complications. J Endocrinol Invest. 2010; 33:118–124. PMID: 19834314.

34. Stote KS, Clevidence BA, Novotny JA, Henderson T, Radecki SV, Baer DJ. Effect of cocoa and green tea on biomarkers of glucose regulation, oxidative stress, inflammation and hemostasis in obese adults at risk for insulin resistance. Eur J Clin Nutr. 2012; 66:1153–1159. PMID: 22854880.

35. Vieira Senger AE, Schwanke CH, Gomes I, Valle Gottlieb MG. Effect of green tea (Camellia sinensis) consumption on the components of metabolic syndrome in elderly. J Nutr Health Aging. 2012; 16:738–742. PMID: 23131813.

36. Huang SM, Chang YH, Chao YC, Lin JA, Wu CH, Lai CY, Chan KC, Tseng ST, Yen GC. EGCG-rich green tea extract stimulates sRAGE secretion to inhibit S100A12-RAGE axis through ADAM10-mediated ectodomain shedding of extracellular RAGE in type 2 diabetes. Mol Nutr Food Res. 2013; 57:2264–2268. PMID: 23901023.

37. Pham NM, Nanri A, Kochi T, Kuwahara K, Tsuruoka H, Kurotani K, Akter S, Kabe I, Sato M, Hayabuchi H, Mizoue T. Coffee and green tea consumption is associated with insulin resistance in Japanese adults. Metabolism. 2014; 63:400–408. PMID: 24342074.

38. Takahashi M, Miyashita M, Suzuki K, Bae SR, Kim HK, Wakisaka T, Matsui Y, Takeshita M, Yasunaga K. Acute ingestion of catechin-rich green tea improves postprandial glucose status and increases serum thioredoxin concentrations in postmenopausal women. Br J Nutr. 2014; 112:1542–1550. PMID: 25230741.

39. Keske MA, Ng HL, Premilovac D, Rattigan S, Kim JA, Munir K, Yang P, Quon MJ. Vascular and metabolic actions of the green tea polyphenol epigallocatechin gallate. Curr Med Chem. 2015; 22:59–69. PMID: 25312214.

40. Dower JI, Geleijnse JM, Gijsbers L, Zock PL, Kromhout D, Hollman PC. Effects of the pure flavonoids epicatechin and quercetin on vascular function and cardiometabolic health: a randomized, double-blind, placebo-controlled, crossover trial. Am J Clin Nutr. 2015; 101:914–921. PMID: 25934864.

41. Peristiowati Y, Indasah I, Ratnawati R. The effects of catechin isolated from green tea GMB-4 on NADPH and nitric oxide levels in endothelial cells exposed to high glucose. J Intercult Ethnopharmacol. 2015; 4:114–117. PMID: 26401396.

42. Dostal AM, Samavat H, Espejo L, Arikawa AY, Stendell-Hollis NR, Kurzer MS. Green tea extract and catechol-O-methyltransferase genotype modify fasting serum insulin and plasma adiponectin concentrations in a randomized controlled trial of overweight and obese postmenopausal women. J Nutr. 2016; 146:38–45. PMID: 26581683.

43. Lu PH, Hsu CH. Does supplementation with green tea extract improve acne in post-adolescent women? A randomized, double-blind, and placebo-controlled clinical trial. Complement Ther Med. 2016; 25:159–163. PMID: 27062963.

44. Sae-tan S, Grove KA, Lambert JD. Weight control and prevention of metabolic syndrome by green tea. Pharmacol Res. 2011; 64:146–154. PMID: 21193040.

45. Nishiumi S, Bessyo H, Kubo M, Aoki Y, Tanaka A, Yoshida K, Ashida H. Green and black tea suppress hyperglycemia and insulin resistance by retaining the expression of glucose transporter 4 in muscle of high-fat diet-fed C57BL/6J mice. J Agric Food Chem. 2010; 58:12916–12923. PMID: 21105694.

46. Islam MS, Choi H. Green tea, anti-diabetic or diabetogenic: a dose response study. Biofactors. 2007; 29:45–53. PMID: 17611293.

47. Jing Y, Han G, Hu Y, Bi Y, Li L, Zhu D. Tea consumption and risk of type 2 diabetes: a meta-analysis of cohort studies. J Gen Intern Med. 2009; 24:557–562. PMID: 19308337.

48. Li Y, Wang C, Huai Q, Guo F, Liu L, Feng R, Sun C. Effects of tea or tea extract on metabolic profiles in patients with type 2 diabetes mellitus: a meta-analysis of ten randomized controlled trials. Diabetes Metab Res Rev. 2016; 32:2–10.

49. Bauer DC, Gaff C, Dinger ME, Caramins M, Buske FA, Fenech M, Hansen D, Cobiac L. Genomics and personalised whole-of-life healthcare. Trends Mol Med. 2014; 20:479–486. PMID: 24801560.