ABSTRACT
Background: By decreasing oxidative stress and whereby decreasing insulin resistance, it may be possible to decrease complications of Diabetes Mellitus [DM]. Green tea and sour tea contain phytochemicals which have anti-oxidative function. The aim of this study is to compare the effect of sour and green tea consumption on insulin resistance and oxidative stress in DM
Methods: This study is a randomized clinical trial in which 100 type 2 diabetes patients were randomly assigned into sour tea group [ST] and green tea group [GT]. The patients were instructed to drink 150ml sour tea and green tea infusion, respectively, three times a day for 4 weeks. Fasting blood sugar [FBS], fructosamine, lipid profiles, fasting blood insulin [FBI], homeostasis model assessment of insulin resistance [HOMA-IR]; beta cell function [b%], insulin sensitivity [S%] and malondialdehyde [MDA] were monitored
Results: HDL-c significantly increased in both groups. The median of FBI in GT showed significant decrease [8.5 to 6.6 micro IU/mL] unlike the ST which showed significant increase [8.2 to 16.3 micro IU/mL]. The median of HOMA-IR after the intervention in GT showed lower levels than the ST [1.1 vs. 1.6, P=0.004]. The median of b% only in ST showed significant increase from 38.2% at the baseline to 47.7% after the intervention. The mean of S% only in ST showed significant decrease after the intervention
Conclusion: This study shows that the use of 150 ml infusion of green tea or sour tea, three times a day for four weeks, has positive effect on insulin resistance and certain lipoproteins in type 2 DM