Diabetes Metab J > Volume 41(4); 2017 > Article |
Values are presented as range or mean±standard deviation.
T2DM, type 2 diabetes mellitus; GTE, green tea extract; GT, green tea; DGTE, decaffeinated green tea extract; EGCG, epigallocatechin gallate.
aAssessed by the CONSORT (CONsolidated Standards of Reporting Trials) checklist for randomized controlled trials.
Study | Design | Participant | Age, yr | Intervention | Control | Treatment duration | Quality of reportinga |
---|---|---|---|---|---|---|---|
Fukino et al. (2008) [16] Japan |
Crossover |
T2DM and pre-diabetes patients (n=60) |
32-73 | GTE beverage (456 mg catechins; 102 caffeine) | Water | 8 weeks | Moderate to high |
Mirzaei et al. (2009) [27] Iran |
Parallel | T2DM patients (n=72) | 54.56±11.23 | GTE capsule (240 mg polyphenols; 150 mg caffeine) | Placebo (cellulose capsules) | 8 weeks | Low |
Nagao et al. (2009) [30] Japan |
Parallel | T2DM patients (n=50) |
64.9±1.6 62.8±2.2 |
GTE beverage (528.8 mg catechins; 75 mg caffeine) | GTE beverage (96.3 mg catechins; 72.3 mg caffeine) | 12 weeks | Moderate to high |
Huyen et al. (2010) [24] Vietnam |
Parallel | T2DM patients (n=24) |
63.5±6.5 57.2±8.2 |
Gynostemma pentaphyllum tea 6 g/day (3 g/packet, twice a day) | GT 6 g/day (3 g/packet, twice a day) | 12 weeks | High |
Hsu et al. (2011) [17] China |
Parallel | T2DM patients (n=68) | 20-65 | DGTE capsule (856 mg EGCG) | Placebo (cellulose capsules) | 16 weeks | High |
Huyen et al. (2013) [25] Vietnam |
Crossover | T2DM patients (n=16) |
58.8±5.9 58.1±6.6 |
Gynostemma pentaphyllum tea 6 g/day (3 g/packet, twice a day) | GT 6 g/day (3 g/packet, twice a day) | 8 weeks | Moderate to high |
Mousavi et al. (2013) [28] Iran |
Parallel | T2DM patients (n=63) | 35-65 | GT (4 cups/day); GT (2 cups/day) | Water (no tea drinks) | 8 weeks | Moderate to high |
Lasaite et al. (2014) [26] Lithuanian |
Parallel | T2DM patients (n=56) | 37-78 | GTE capsules (200 mg polyphenols) | Placebo (cellulose capsules) | 18 months | Low |
Liu et al. (2014) [19] China | Parallel | T2DM patients (n=77) |
55.0±6.6 53.5±7.0 |
DGTE capsule (856.8 mg EGCG) | Placebo (cellulose capsules) | 16 weeks | High |
Mozaffari-Khosravi et al. (2014) [29] Iran |
Parallel | T2DM patients (n=94) |
52.2±6.7 52.1±6.0 |
GT bag (3 g/day) | Sour tea bag (3 g/day) | 4 weeks | High |
Ryu et al. (2006) [31] Korea |
Crossover | T2DM patients (n=55) | 53.9±7.7 | GTE beverage (9 g GT) | Water | 4 weeks | Very low |
Study | Outcomes | Assessment point | Results (intervention vs. control) |
---|---|---|---|
Fukino et al. (2008) [16] | FI, FG, HOMA-IR, HbA1c |
T0: baseline T1: 4 weeks |
HbA1c (%): T0: 6.2±2.0 vs. 6.1±1.3, P=0.03; T1: 5.9±1.9 vs. 6.1±1.4 FG (mmol/L): T0: 7.5±3.5 vs. 7.7±2.5, P=0.18; T1: 7.0±2.7 vs. 7.2±1.6 FI (µU/mL): T0: 8.8±7.3 vs. 10.3±10.1, P=0.41; T1: 7.4±7.3 vs. 6.5±4.0 HOMA-IR: T0: 3.0±2.9 vs. 3.7±4.4, P=0.35; T1: 2.4±2.5 vs. 2.1±1.3 |
Mirzaei et al. (2009) [27] | HbA1c, FI, FG |
T0: baseline T1: 8 weeks |
HbA1c (%): T0: 7.21±1.63 vs. 7.61±2.04, P=0.3; T1: 7.25±1.87 vs. 8.17±2.09, P=0.05 FG (mmol/L): T0: 162.71±65.72 vs. 175.90±62.39, P=0.7; T1: 169.07±70.60 vs. 185.51±72.75, P=0.15 FI (µU/mL): T0: 15.92±7.42 vs. 14.13±4.39, P=0.3; T1: 16.70±8.99 vs. 15.57±7.03, P=0.06 |
Nagao et al. (2009) [30] | FI, FG, HbA1c |
T0: baseline T1: 12 weeks |
T0-T1 Changes: HbA1c (%): -0.37±0.12 vs. -0.01±0.17 FG (mg/dL): -8.0±4.7 vs. 4.9±5.7 FI (µU/mL): 1.78±0.81 vs. -0.55±0.46 |
Huyen et al. (2010) [24] | FI, FG, HbA1c, HOMA-IR |
T0: baseline T1: 12 weeks |
T0-T1 Changes: HbA1c (%): 2.0±1.3 vs. 0.2±0.5 FG (mmol/L): -3.0±1.8 vs. -0.6±2.2, P=0.007 FI (pmol/L): -6.0±42.9 vs. -22.5±47.5, P=0.147 HOMA-IR: -2.14±3.05 vs. 1.1±3.27, P=0.023 |
Hsu et al. (2011) [17] | FI, FG, HOMA-IR, HbA1c |
T0: baseline T1: 16 weeks |
T0-T1 Changes: HbA1c (%): 4.3±9.1 vs. 3.0±9.0, P=0.54 FG (mmol/L): 0.26±1.58 vs. 0.15±1.25, P=0.76 FI (UI/L): 11.0±47.6 vs. -0.4±65.1, P=0.41 HOMA-IR: 11.1± 62.2 vs. 2.4±62.7, P=0.57 |
Huyen et al. (2013) [25] | FI, FG |
T0: baseline T1: 4 weeks |
T0-T1 Changes: FG (mmol/L): -1.9±1.0 vs. -0.2±1.5, P<0.001 FI (pmol/L): -0.23±7.8 vs. -0.3±9.8, P=0.984 |
Mousavi et al. (2013) [28] | FG |
T0: baseline T1: 8 weeks |
FG: T0: 142.0±42.0 vs. 144.3±44.9 ; T1: 143.6±43.9 vs. 142.9±3.2 |
Lasaite et al. (2014) [26] | HbA1c |
T0: baseline T1: 9 months |
HbA1c (%): T0: 7.8±1.4 vs. 8.1±2.0; T1: 7.5±1.3 vs. 7.5±1.5 |
Liu et al. (2014) [19] | FI, FG, HOMA-IR, HbA1c |
T0: baseline T1: 16 weeks |
T0-T1 Changes: FG (mg/dL): 9.0±30.3 vs. -0.6±25.2, P=0.13 HbA1c (%): 0.0±5.5 vs. -0.2±0.6, P=0.24 FI (IU/L): -6.3±10.0 vs. -4.7±13.5, P=0.54 HOMA-IR: -0.20±4.0 vs. 1.3±4.8, P=0.50 |
Mozaffari-Khosravi et al. (2014) [29] | FG, HOMA-IR |
T0: baseline T1: 4 weeks |
T0-T1 Changes: FG (mg/dL): -1.6±26 vs. 1.2±26, P=0.5 HOMA-IR: T0: 1.20 vs. 1.30, P=0.6; T1: 1.60 vs. 1.10, P=0.004 |
Ryu et al. (2006) [31] | FI, FG, HOMA-IR |
T0: baseline T1: 4weeks |
T0- T1 Changes: FG (mmol/L): 6.7±1.3 vs. 6.9±1.1, P=0.09 FI (µU/mL): 10.29±1.69 vs. 10.40±1.47, P=0.71 HOMA-IR: 2.99±1.71 vs. 3.15±1.51, P=0.45 |
Excluded study | Reasons for exclusion |
---|---|
MacKenzie et al. (2007) [32] | Intervention are combined green tea and black tea |
Fenercioglu et al. (2010) [33] | Intervention are combined green tea and pomegranate extract |
Stote et al. (2012) [34] | Participants are neither T2DM or pre-diabetes patients |
Vieira Senger et al. (2012) [35] | Participants are neither T2DM or pre-diabetes patients |
Huang et al. (2013) [36] | Not RCT |
Pham et al. (2014) [37] | Participants are neither T2DM or pre-diabetes patients |
Takahash et al. (2014) [38] | No targeted outcomes reported |
Keske et al. (2015) [39] | Not RCT |
Dower et al. (2015) [40] | Participants are neither T2DM or pre-diabetes patients |
Peristiowati et al. (2015) [41] | Not RCT |
Dostal et al. (2016) [42] | Participants are neither T2DM or pre-diabetes patients |
Lu et al. (2016) [43] | Participants are neither T2DM or pre-diabetes patients |
Ashley R. Cooper
https://orcid.org/0000-0001-8644-3870
National Institute for Health Research (NIHR) Bristol Nutrition Biomedical Research Unit