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 .
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 ) .
Antidiabetic effect of Gynostemma pentaphyllum tea in randomly assigned type 2 diabetic patients.
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
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 .
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 ) .