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

Clin Nutr ESPEN. 2017 Dec;22:1-6. doi: 10.1016/j.clnesp.2017.08.008. Epub 2017 Aug 31.

Abstract

Background & aims: 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.

Methods: A total of 120 overweight women were randomly assigned in a double-blind manner to 1 of 4 groups, as follows: control (n = 29; 1 g of cellulose), green tea (n = 32; 1 g of dry green tea extract), metformin (n = 28; 1 g of metformin), and green tea + metformin (n = 31; 1 g of dry green tea extract + 1 g of metformin). Each group took the indicated capsules daily for 12 weeks. Anthropometric measurements, body composition, and fasting blood samples were evaluated.

Results: 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 ± 0.366 kg; 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.

Conclusions: 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.

Keywords: Camellia sinensis; Insulin resistance; Lipoproteins LDL; Metformin; Obesity.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • Body Composition
  • Body Mass Index
  • Cholesterol / blood
  • Diabetes Mellitus, Type 2
  • Dietary Carbohydrates / administration & dosage
  • Dietary Fats / administration & dosage
  • Dietary Fiber / administration & dosage
  • Dietary Proteins / administration & dosage
  • Double-Blind Method
  • Female
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Metformin / pharmacology*
  • Middle Aged
  • Overweight / blood
  • Overweight / drug therapy*
  • Plant Extracts / pharmacology*
  • Tea / chemistry*
  • Triglycerides / blood
  • Young Adult

Substances

  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats
  • Dietary Fiber
  • Dietary Proteins
  • Glycated Hemoglobin A
  • Plant Extracts
  • Tea
  • Triglycerides
  • Metformin
  • Cholesterol