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Suk, Kim, Ju, Han, and Park: The Effect of Green Tea Polyphenol on Plasma Glucose, Lipid Levels and Antioxidant Systems in Type 2 Diabetic Patients
Original Article
The Journal of Korean Diabetes Association

The Journal of Korean Diabetes Association 2006; 30(3): 217-225.

Published online: 31 May 2006

DOI: https://doi.org/10.4093/jkda.2006.30.3.217

The Effect of Green Tea Polyphenol on Plasma Glucose, Lipid Levels and Antioxidant Systems in Type 2 Diabetic Patients

Ji Hye Suk, Mi Kyung Kim, Jae Won Ju1, Ji Sook Han1, Jeong Hyun Park2

Department of Internal Medicine, Maryknoll General Hospital, Korea.

1Department of Food Science and Nutrition, Pusan National University, Korea.

2Department of Internal Medicine, Pusan Palk Hospital College of Medicine, Inje University, Korea.

Received 17 February 2006       Accepted 26 May 2006

Copyright © 2006 Korean Diabetes Association

Abstract

Background

Green-tea polyphenol (GTP) is a well known antioxidant with favorable effect on blood glucose and lipid level in animal models. We were to investigate the effects of GTP on plasma glucose, lipid and antioxidant systems in patients with type 2 diabetes.

Methods

We recruited non-complicated type 2 diabetic patients with stable glycemic control by oral hypoglycemic agents. Subjects were randomly assigned to GTP group or placebo group for 12 weeks. Fasting plasma glucose (FPG), HbA1c, C-peptide, lipid levels, liver function test, renal function test, urine microalbumin, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities were measured at baseline and after 12 weeks of treatment.

Results

At baseline, there were no significant differences in age, body mass index, duration of diabetes, dietary status, HbA1c, total cholesterol, LDL cholesterol, and HDL cholesterol levels between GTP and placebo group. However, FPG levels and triglyceride levels were significantly different between GTP and placebo group at baseline. In both of GTP and placebo group, there were no significant change after 12 weeks of treatment in FPG, HbA1c, total cholesterol, LDL cholesterol, triglyceride, levels of MDA, and GSHPx activities. SOD activities significantly increased after 12 weeks of treatment in both of GTP and placebo group. The increase of SOD activities were significantly higher in GTP group than in placebo group (P = 0.01).

Conclusions

Supplementation of green tea polyphenol increased antioxidant activity in type 2 diabetic patients. The effect on plasma glucose and lipid level was not significant but should be confirmed in further large scaled studies.

Keywords: Antioxidant, Lipid, Glucose, Green tea polyphenol, Type 2 Diabetes Mellitus

Figures and Tables

Fig. 1
Changes in superoxide dismutase activities after 12 weeks treatment of green tea polyphenol or placebo.
There were significant differences between baseline and after 12 weeks of treatment in both placebo group and green tea polyphenol group (P < 0.05 by paired-t test).
*There was a significant difference between placebo and green tea polyphenol group (P = 0.11 by repeated measure general linear models).
jkda-30-217-g001
Table 1
Baseline Characteristics of Study Subjects
jkda-30-217-i001

Values are means ± standard deviations.

P values are calculated by independent-t test between placebo group and green tea polyphenol group.

Table 2
Changes of Clinical and Laboratory Characteristics After 12 Weeks Treatment of Green Tea Polyphenol or Placebo
jkda-30-217-i002

Values are means ± standard deviations.

*P values are calculated by repeated measures general linear models between placebo and green tea polyphenol group on difference of between their baseline and after 12 weeks of treatment.

†P < 0.05 caculated by independent-t test for comparison between placebo group and green tea polyphenol group.

‡P < 0.05 caculated by paired-t test for comparison between baseline and after 12 weeks of treatment.

Table 3
Changes of MDA, SOD, GSHPx Activities After 12 Weeks Treatment of Green Tea Polyphenol or Placebo
jkda-30-217-i003

Values are means ± standard deviations.

*P values are calculated by repeated measures general linear models between placebo and green tea polyphenol group on difference between their baseline and after 12 weeks of treatment.

†P < 0.05 calculated by paired-t test for comparison between baseline and after 12 weeks of treatment.

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