Effects of Green Tea Extract on Insulin Resistance and Glucagon-Like Peptide 1 in Patients with Type 2 Diabetes and Lipid Abnormalities: A Randomized, Double-Blinded, and Placebo-Controlled Trial

Abstract

The aim of this study is to investigate the effect of green tea extract on patients with type 2 diabetes mellitus and lipid abnormalities on glycemic and lipid profiles, and hormone peptides by a double-blinded, randomized and placebo-controlled clinical trial. This trial enrolled 92 subjects with type 2 diabetes mellitus and lipid abnormalities randomized into 2 arms, each arm comprising 46 participants. Of the participants, 39 in therapeutic arm took 500 mg green tea extract, three times a day, while 38 in control arm took cellulose with the same dose and frequency to complete the 16-week study. Anthropometrics measurements, glycemic and lipid profiles, safety parameters, and obesity-related hormone peptides were analyzed at screening and after 16-week course. Within-group comparisons showed that green tea extract caused a significant decrease in triglyceride and homeostasis model assessment of insulin resistance index after 16 weeks. Green tea extract also increased significantly high density lipoprotein cholesterol. The HOMA-IR index decreased from 5.4±3.9 to 3.5±2.0 in therapeutic arm only. Adiponectin, apolipoprotein A1, and apolipoprotein B100 increased significantly in both arms, but only glucagon-like peptide 1 increased in the therapeutic arm. However, only decreasing trend in triglyceride was found in between-group comparison. Our study suggested that green tea extract significantly improved insulin resistance and increased glucagon-like peptide 1 only in within-group comparison. The potential effects of green tea extract on insulin resistance and glucagon-like peptide 1 warrant further investigation.Trial RegistrationClinicalTrials.gov NCT01360567

The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials

“…A study by [14] evaluated the effects of GTE supplementation over the course of 16 weeks on the lipid profiles of 102 subjects diagnosed with type 2 diabetes and dyslipidemia; this study was also located in an outpatient clinic in Taipei However, when the variations in the aforementioned parameters were evaluated between the two subject groups, no significant differences were found. Thus, the authors claimed that the supplement did not offer any decrease in the participants' lipids, glucose, or weight parameters.…”

“…It was beyond the scope of this review to include and examine sources from 'grey' literature. Despite the variability of effect, with some studies finding conflicting outcomes [28][29][30], the majority of the current literature appears to support the positive therapeutic effect derived from GT consumption [1,[9][10][11][12][13][14][15][31][32][33][34]. Furthermore, as tea consumption is high globally, it could be proposed that even modest health effects in humans may have major beneficial implications for global population health and reduction in CVD risk [21,35].…”

“…Of which, 30 were excluded on the basis of: study design (n = 16), missing outcome data (n = 14), and absence of placebo group (n = 1). The seven remaining studies [9][10][11][12][13][14][15] met the inclusion criteria (Table 1), with a cumulative total of 466 participants aged from 16 to 65, with an average age of 47.7˘9.2 years (mean˘SD). Five of the chosen studies [9][10][11][12][13][14][15] included participants of both gender, whilst the remaining three [10,11,13] examined the effects of GT extract supplementation in females only.…”

“…Five of the chosen studies [9][10][11][12][13][14][15] included participants of both gender, whilst the remaining three [10,11,13] examined the effects of GT extract supplementation in females only. Furthermore, five of the chosen studies [9][10][11][12][13] investigated the effect of interventions on obese participants, two examined people with type 2 diabetes [14,15], and one studied healthy individuals ( Table 1).…”

“…with a majority of the chosen articles presenting with a low risk of bias for categories of selection, performance, detection, attrition, and reporting methods (Table 2). However, it should be noted that three studies [11,14,15] were determined as being moderately at risk of selection bias. One study [13] showed moderate risk of attrition bias and another study [11] was deemed to have an unclear risk of bias, as attrition rate was not mentioned in the article.…”