title: 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. Does supplementation with green tea extract improve insulin resistance in obese type 2 diabetics? A randomized, double-blind, and placebo-controlled clinical trial. Acute ingestion of catechin-rich green tea improves postprandial glucose status and increases serum thioredoxin concentrations in postmenopausal women. Antidiabetic effect of Gynostemma pentaphyllum tea in randomly assigned type 2 diabetic patients. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Does supplementation with green tea extract improve acne in post-adolescent women? A randomized, double-blind, and placebo-controlled clinical trial. Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice Effect of cocoa and green tea on biomarkers of glucose regulation, oxidative stress, inflammation and hemostasis in obese adults at risk for insulin resistance The Effect of Ginkgo biloba and Camellia sinensis Extracts on Psychological State and Glycemic Control in Patients with Type 2 Diabetes Mellitus Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. 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. CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials
abstract: BACKGROUND Green tea consumption has been associated with favorable changes in body weight and obesity-related hormones , although it is not known whether these changes result from green tea polyphenols or caffeine . OBJECTIVE We examined the impact of decaffeinated green tea extract ( GTE ) containing 843 mg of (-)-epigallocatechin-3-gallate on anthropometric variables , obesity-associated hormones , and glucose homeostasis . METHODS The Minnesota Green Tea Trial was a 12-mo r and omized , double-blind , placebo-controlled clinical trial of 937 healthy postmenopausal women assigned to either decaffeinated GTE ( 1315 mg total catechins/d ) or a placebo  , stratified by catechol-O-methyltransferase ( COMT ) genotype . This study was conducted in a subset of 237 overweight and obese participants [ body mass index ( BMI ) ≥25 kg/m(2 ) ] . RESULTS No changes in energy intake , body weight , BMI , or waist circumference ( WC ) were observed over 12 mo in women taking GTE ( n = 117 ) or placebo ( n = 120 ) . No differences were seen in circulating leptin , ghrelin , adiponectin , or glucose concentrations at month 12 . Participants r and omly assigned to GTE with baseline insulin ≥10 μIU/mL ( n = 23 ) had a decrease in fasting serum insulin from baseline to month 12 ( -1.43 ± 0.59 μIU/mL ) , whereas those r and omly assigned to placebo with baseline insulin ≥10 μIU/mL ( n = 19 ) had an increase in insulin over 12 mo ( 0.55 ± 0.64 μIU/mL , P < 0.01 ) . Participants with the homozygous high-activity ( G/G ) form of COMT had significantly lower adiponectin ( 5.97 ± 0.50 compared with 7.58 ± 0.53 μg/mL , P = 0.03 ) and greater insulin concentrations ( 7.63 ± 0.53 compared with 6.18 ± 0.36 μIU/mL , P = 0.02 ) at month 12 compared with those with the low-activity ( A/A ) genotype , regardless of treatment group . CONCLUSIONS Decaffeinated GTE was not associated with reductions in body weight , BMI , or WC and did not alter energy intake or mean hormone concentrations in healthy postmenopausal women over 12 mo . GTE decreased fasting insulin concentrations in those with elevated baseline fasting concentrations . The high-activity form of the COMT enzyme may be associated with elevations in insulin and a reduction in adiponectin concentrations over time . This trial was registered at http://www . clinical trials.gov as NCT00917735 BACKGROUND Green tea is one of the most popular beverages in the world . It is believed to have beneficial effects in the prevention and treatment of many diseases , one of which is type 2 diabetes . The aim of the study is to examine the effect of a decaffeinated green tea extract ( GTE ) providing a daily dose of 856 mg of epigallocatechin gallate ( EGCG ) on obese individuals with type 2 diabetes . MATERIAL S AND METHODS The clinical trial was a r and omized , double-blind , placebo-controlled clinical trial conducted from December 2007 through November 2008 . The subjects were r and omly assigned to either receive 1,500 mg of a decaffeinated GTE or placebo daily for 16 weeks . Sixty-eight of 80 subjects , ages 20 - 65 years with BMI > 25 kg/m2 and type 2 diabetes for more than one year , completed this study .  Homeostasis model assessment for insulin resistance ( HOMA-IR ) was used as the major outcome measurement . At baseline and after 16 weeks of treatment , anthropometric measurements , fasting glucose , hemoglobin A1C percent ( HbA1C ) , hormone peptides , and plasma lipoproteins were measured from both groups . RESULTS No statistically significant differences were detected between the decaffeinated GTE and placebo groups in any measured variable . A statistically significant within-group 0.4-percent reduction in HbA1C ( from 8.4 to 8.0 % ) was observed after GTE treatment compared to baseline . Within-group comparison also revealed that the GTE group had significant reductions in waist circumference ( WC ) , HOMA-IR index , and insulin level , and a significant increase in the level of ghrelin . Within-group comparison of those in the placebo group showed a significant increase in the level of ghrelin . CONCLUSIONS This study found no statistical difference in any measured variable between the decaffeinated GTE and placebo groups ; however , there were some statistically significant within-group changes detected . More research is required to determine whether a decaffeinated GTE st and ardized for EGCG content will provide any clinical benefits in obese individuals with type 2 diabetes . Clinical Trial Registration NO : NCT00567905 Elevated postpr and ial hyperglycaemia and oxidative stress increase the risks of type 2 diabetes and CVD . Green tea catechin possesses antidiabetic properties and antioxidant capacity . In the present study , we examined the acute and continuous effects of ingestion of catechin-rich green tea on postpr and ial hyperglycaemia and oxidative stress in healthy postmenopausal women . Participants were r and omly assigned into the  placebo ( P , n 11 ) or green tea ( GT , n 11 ) group . The GT group consumed a catechin-rich green tea ( catechins 615 mg/350 ml ) beverage per d for 4 weeks . The P group consumed a placebo ( catechins 92 mg/350 ml ) beverage per d for 4 weeks . At baseline and after 4 weeks , participants of each group consumed their design ated beverages with breakfast and consumed lunch 3 h after breakfast . Venous blood sample s were collected in the fasted state ( 0 h ) and at 2 , 4 and 6 h after breakfast . Postpr and ial glucose concentrations were 3 % lower in the GT group than in the P group ( three-factor ANOVA , group × time interaction , P < 0·05 ) . Serum concentrations of the derivatives of reactive oxygen metabolites increased after meals ( P < 0·05 ) , but no effect of catechin-rich green tea intake was observed . Conversely , serum postpr and ial thioredoxin concentrations were 5 % higher in the GT group than in the P group ( three-factor ANOVA , group × time interaction , P < 0·05 ) . These findings indicate that an acute ingestion of catechin-rich green tea has beneficial effects on postpr and ial glucose and redox homeostasis in postmenopausal women The aim of the study was to investigate the antidiabetic effect of the traditional Vietnamese herb Gynostemma pentaphyllum in 24 drug-naïve type 2 diabetic patients . All patients were r and omized to authenticated Gynostemma pentaphyllum tea or placebo tea , 6 g daily , during twelve weeks and received information regarding diet and exercise .  Fasting plasma glucose , insulin levels , and glycosylated hemoglobin ( HbA(1C ) ) were measured before , during , and after the treatment . Oral glucose tolerance tests were performed every four weeks . After 12-week treatment , fasting plasma glucose levels totally decreased to an extent of 3.0+/-1.8 mmol/l in the Gynostemma pentaphyllum tea group as compared to a decrease of 0.6+/-2.2 mmol/l in the control group ( p<0.01 ) . HbA(1C ) levels after 12 weeks decreased approximately 2 % units in the Gynostemma pentaphyllum group compared to 0.2 % unit in the controls ( p<0.001 ) . Change in Homeostasis Model Assessment -Insulin Resistance between baseline and twelfth week indicated that insulin resistance decreased significantly in the Gynostemma pentaphyllum group ( -2.1+/-3.0 ) compared with that ( + 1.1+/-3.3 ) in the control group ( p<0.05 ) . There were no hypoglycemias , or adverse effects regarding kidney and liver parameters or gastrointestinal function . In addition , lipid profiles , glucagon , cortisol levels , body measurements , and blood pressure were not different between the groups . This study shows a prompt improvement of glycemia and insulin sensitivity , and thereby provides a basis for a novel , effective , and safe approach , using Gynostemma pentaphyllum tea , to treat type 2 diabetic patients Recent evidence suggests that tea from Camellia sinensis ( eg , green , oolong , and black tea ) may have a hypoglycemic effect . We evaluated the ability of an extract of green and black tea to improve glucose control over a 3-month period . A double-blind , placebo-controlled , r and omized multiple-dose ( 0 , 375 , or 750 mg per day for 3 months ) study in adults with type 2 diabetes mellitus not taking insulin was performed . The primary end point was change in glycosylated hemoglobin at 3 months . The 49 subjects who completed this study were predominantly white with an average age of 65 years and a median duration of diabetes of 6 years , and 80 % of them reported using hypoglycemic medication .  After 3 months , the mean changes in glycosylated hemoglobin were + 0.4 ( 95 % confidence interval , 0.2 - 0.6 ) , + 0.3 ( 0.1 - 0.5 ) , and + 0.5 ( 0.1 - 0.9 ) in the placebo , 375-mg , and 750-mg arms , respectively . The changes were not significantly different between study arms . We did not find a hypoglycemic effect of extract of green and black tea in adults with type 2 diabetes mellitus BACKGROUND Green tea is believed to have beneficial effects in the prevention and treatment of acne . OBJECTIVE To examine the effects of a decaffeinated green tea extract ( GTE ) , providing a daily dose of 856 mg of epigallocatechin gallate ( EGCG ) upon women with post-adolescent acne . METHODS A r and omized , double-blind , placebo-controlled clinical trial was conducted from May 2012 through October 2013 . A final group of 80 subjects were r and omly assigned to receive either 1500 mg of decaffeinated GTE or placebo ( cellulose ) daily for 4 weeks . Inflammatory lesion counts were used as the major outcome measurement . At baseline and after 4 weeks of treatment , anthropometric measurements , fasting glucose levels and a lipid profile were measured from both groups . RESULTS Sixty-four of 80 women , from 25 to 45 years of age with moderate-to-severe acne completed the study . Statistically significant differences were noted in inflammatory lesion counts distributed on the nose , periorally and on the chin between the two groups . However , there were no significant differences between groups for total lesion counts . Within-group comparison revealed that the GTE group had significant reductions in inflammatory lesions distributed on the forehead and cheek , and significant reductions in total lesion counts . GTE result ed in significant reductions in total cholesterol levels within the GTE group . CONCLUSIONS GTE result ed in significant reductions in lesions located on the nose , perioral area and chin . More research is required to determine whether a decaffeinated GTE st and ardized for EGCG content will provide clinical benefits in women with post-adolescent acne Background Green tea was suggested as a therapeutic agent for the treatment of diabetes more than 70 years ago , but the mechanisms behind its antidiabetic effect remains elusive . In this work , we address this issue by feeding a green tea extract ( TEAVIGO ™ ) with a high content of epigallocatechin gallate ( EGCG ) or the thiazolidinedione PPAR-γ agonist rosiglitazone , as positive control , to db/db mice , an animal model for diabetes . Methods Young ( 7 week-old ) db/db mice were r and omized and assigned to receive diets supplemented with or without EGCG or rosiglitazone for 10 weeks . Fasting blood glucose , body weight and food intake was measured along the treatment . Glucose and insulin levels were determined during an oral glucose tolerance test after 10 weeks of treatment . Pancreata were sample d at the end of the study for blinded histomorphometric analysis . Islets were isolated and their mRNA expression analyzed by quantitative RT-PCR . Results The results show that , in db/db mice , EGCG  improves glucose tolerance and increases glucose-stimulated insulin secretion . EGCG supplementation reduces the number of pathologically changed islets of Langerhans , increases the number and the size of islets , and heightens pancreatic endocrine area . These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers , possibly linked to the antioxidative capacity of EGCG . Conclusions This study shows that the green tea extract EGCG markedly preserves islet structure and enhances glucose tolerance in genetically diabetic mice . Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes Background / Objectives : Flavanols may provide protection against insulin resistance , but little is known about the amounts and types of flavanols that may be efficacious . Subjects/ Methods : This study was design ed to determine whether cocoa flavanols , over a range of intakes , improve biomarkers of glucose regulation , inflammation and hemostasis in obese adults at risk for insulin resistance . As an adjunct , green tea and cocoa flavanols were compared for their ability to modulate these biomarkers . In a r and omized crossover design , 20 adults consumed a controlled diet for 5 days along with four cocoa beverages containing 30–900 mg flavanol per day , or tea matched to a cocoa beverage for monomeric flavanol content . Results : Cocoa beverages produced no significant changes in glucose , insulin , total area under the concentration – time curve ( AUC ) for glucose or total insulin AUC . As the dose of cocoa flavanols increased , total 8-isoprostane concentrations were lowered ( linear contrast , P=0.02 ) , as were C-reactive protein ( CRP ) concentrations ( linear contrast , P=0.01 ) . The relationship between cocoa flavanol levels and interleukin-6 ( IL-6 ) concentrations was quadratic , suggesting that a maximum effective dose was achieved ( quadratic contrast , P=0.01 ) . There were no significant effects on measured indices of glucose regulation , nor on those of total 8-isoprostane , CRP and IL-6 concentrations , when cocoa and green tea were compared . However , relative to cocoa , green tea  lowered fibrinogen concentrations ( P=0.0003 ) . Conclusions : Short-term intake of cocoa and green tea flavanols does not appear to improve glucose metabolism ; they do affect selected markers of one or more measures of oxidative stress , inflammation or hemostasis in obese adults at risk for insulin resistance Interest in finding natural antioxidants for use in food or medical material s to prevent free radical imbalance has increased considerably over the past years . The aim of this research was to evaluate changes in glycemic control and psychological state of patients with type 2 diabetes mellitus ( T2DM ) after use of antioxidant plant preparations .  Fifty-six patients with T2DM were r and omly allocated to receive st and ardized Ginkgo biloba L. leaves dry extract , green tea dry extract , or placebo capsules .  Diabetes glycemic control measured as glycated hemoglobin ( HbA1c ) level , antioxidant state and psychological data were evaluated at baseline , after 9 and 18 months of using either antioxidant preparations or placebo . The level of perceived stress lowered significantly after 9 months ( p=0.038 ) and 18 months ( p=0.030 ) , and the psychological aspect of quality of life significantly improved after 18 months ( p=0.019 ) of use of G. biloba extract . No significant differences were detected after using green tea extract . In patients using placebo , significant lowering of HbA1c level was observed after 18 months ( p=0.017 ) . In conclusion , antioxidant G. biloba leaf extract exhibited a mild effect on psychological state and a trend of improving glycemic control in patients with type 2 diabetes mellitus BACKGROUND Type 2 diabetes affects approximately 8 percent of adults in the United States . Some risk factors -- elevated plasma glucose concentrations in the fasting state and after an oral glucose load , overweight , and a sedentary lifestyle -- are potentially reversible . We hypothesized that modifying these factors with a lifestyle-intervention program or the administration of metformin would prevent or delay the development of diabetes . METHODS We r and omly assigned 3234 nondiabetic persons with elevated fasting and post-load plasma glucose concentrations to placebo , metformin ( 850 mg twice daily ) , or a lifestyle-modification program  with the goals of at least a 7 percent weight loss and at least 150 minutes of physical activity per week . The mean age of the participants was 51 years , and the mean body-mass index ( the weight in kilograms divided by the square of the height in meters ) was 34.0 ; 68 percent were women , and 45 percent were members of minority groups . RESULTS The average follow-up was 2.8 years . The incidence of diabetes was 11.0 , 7.8 , and 4.8 cases per 100 person-years in the placebo , metformin , and lifestyle groups , respectively . The lifestyle intervention reduced the incidence by 58 percent ( 95 percent confidence interval , 48 to 66 percent ) and metformin by 31 percent ( 95 percent confidence interval , 17 to 43 percent ) , as compared with placebo ; the lifestyle intervention was significantly more effective than metformin . To prevent one case of diabetes during a period of three years , 6.9 persons would have to participate in the lifestyle-intervention program , and 13.9 would have to receive metformin . CONCLUSIONS Lifestyle changes and treatment with metformin both reduced the incidence of diabetes in persons at high risk . The lifestyle intervention was more effective than metformin The receptor for advanced glycation of end products ( RAGE ) plays a critical role in the progression of type 2 diabetes ( T2D ) . Soluble RAGE ( sRAGE ) is one of the RAGE variants , which acts as a decoy domain receptor and competes with RAGE , thus contributing to prevention of T2D . In this study , we conducted clinical trials of (-)-epigallocatechin-3-gallate ( EGCG ) rich green tea extract ( 300 - 900 mg/day ) to investigate the effect of EGCG on relationship between S100A12 RAGE lig and and diverse sRAGE in T2D . Moreover , mechanism of sRAGE production also confirmed in vitro . Our data indicated that EGCG could stimulate sRAGE circulation but inhibited RAGE lig and in T2D , and ADAM10-mediated ectodomain shedding of extracellular RAGE was mainly involved in EGCG-stimulated sRAGE circulation . The present evidence indicates that EGCG has a potential to block S100A12-RAGE axis by stimulating sRAGE production through ADAM10-mediated ectodomain shedding of extracellular RAGE . Therefore , EGCG contributes to nutritional strategies for diabetes , not only because of its efficient antioxidant activity to scavenge free radicals , but also because of its ability stimulating sRAGE release in the circulation . Additionally , ADAM10-induced ectodomain shedding of extracellular RAGE leading to sRAGE circulation should be a potential of passive mechanism of sRAGE production to block S100A12-RAGE axis-related pathogenesis of proinflammation and diabetes The CONSORT statement is used worldwide to improve the reporting of r and omised controlled trials . Kenneth Schulz and colleagues describe the latest version , CONSORT 2010 , which up date s the reporting guideline based on new method ological evidence and accumulating experience . To encourage dissemination of the CONSORT 2010 Statement , this article is freely accessible on bmj.com and will also be published in the Lancet , Obstetrics and Gynecology , PLoS Medicine , Annals of Internal Medicine , Open Medicine , Journal of Clinical Epidemiology , BMC Medicine , and Trials
target: 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 .
background: 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 ) .