Green tea extract outperforms metformin in lipid profile and glycaemic control in overweight women: A double-blind, placebo-controlled, randomized trial

Abstract

Both green tea and metformin are used as adjuvants to treat and prevent complications associated with obesity; however, studies comparing their action and interaction in non-diabetic overweight women have not been reported. Thus, the current study evaluated the effects of green tea extract and metformin, both individually and in combination, on type 2 diabetes risk factors in non-diabetic overweight women. A total of 120 overweight women were randomly assigned in a double-blind manner to 1 of 4 groups, as follows: control (n=29; 1g of cellulose), green tea (n=32; 1g of dry green tea extract), metformin (n=28; 1g of metformin), and green tea+metformin (n=31; 1g of dry green tea extract+1g of metformin). Each group took the indicated capsules daily for 12 weeks. Anthropometric measurements, body composition, and fasting blood samples were evaluated. Although no significant interactions were observed in glycaemic control (p=0.07), green tea in the absence of metformin reduced fasting glucose (-4.428±2.00; p=0.031), but when combined the lowering effect was nullified. In contrast, metformin increased HbA1c concentration (0.048±0.189%; p=0.017) and also reduced body weight (-1.318±0.366kg; p=0.034) and LM (lean mass) (-1.249±0.310; p=0.009). Regarding lipid parameters, green tea significantly reduced total cholesterol and LDL-c. Green tea was superior to metformin in improving glycaemic control and lipid profile in non-diabetic overweight women and, therefore, green tea extract is a promising alternative for reducing type 2 diabetes risk in overweight women.