Abstract :
Keywords Green tea; Blood pressure; Type 2 diabetes; Meta-analysis; Review Abstract Background and objectives Previous trials conducted on patients with type 2 diabetes mellitus (T2DM) showed controversial results regarding the efficacy of green tea (GT) in improving blood pressure (BP). We conducted a review and meta-analysis of randomized controlled trials (RCTs) to summarize the effect of GT supplementation on BP among patients with T2DM. Methods and study design Online databases, including PubMed/Medline, Scopus, and ISI web of science, were searched up to March 2021 to retrieve RCTs that examined the effect of GT on BP in patients with T2DM. Meta-analyses were carried out using a random effects model. The I2 index was used to evaluate the heterogeneity. Results Among the initial 854 studies identified from electronic databases search, ten trials, which included 681 participants, were eligible. Pooled effect size from 10 studies indicated that supplementary intake of GT had no significant effect on systolic blood pressure (SBP) (Mean Difference (MD): 0.00 mmHg, 95 % CI: (-0.01, 0.01), p = 0.997), with no significant heterogeneity between the studies (I2 = 8.8 %, p = 0.356) and diastolic blood pressure (DBP) (MD: -0.90 mmHg, 95 % CI: (-2.21, 0.41), p = 0.178), with significant heterogeneity among the studies (I2 = 55.6 %, p = 0.006). Subgroup analysis revealed that GT supplementation lowers DBP when intervention is conducted on patients with elevated DBP. Conclusion Our meta-analysis revealed that although GT supplementation has no significant effect on general BP in patients with T2DM, it may significantly improve DBP in patients with T2DM who have high DBP. Author Affiliation: (a) Nutrition and Metabolic Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran (b) Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran (c) Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran (d) PhD Student at Department of Dietetics and Nutrition Robert Stempel College of Public Health & Social Work Florida International University, United States (e) Department of Clinical Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran (f) Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran (g) Department of Food Industry, Islamic Azad University North Branch, Tehran, Iran (h) Faculty Member of IR of Iran Ministry of Health & Medical Education, Iran (i) Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran (j) Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran (k) Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran * Corresponding author. Article History: Received 11 January 2021; Revised 21 October 2022; Accepted 9 December 2022 Byline: Damoon Ashtary-Larky [damoon_ashtary@yahoo.com] (a), Sara Niknam [saraniknam65@yahoo.com] (b), Mohammad Javad Alaeian [javadalaeian@gmail.com] (c), Maryam Nadery [mnade017@fiu.edu] (d), Reza Afrisham [rezaafrisham@yahoo.com] (e), Faezeh Fouladvand [foladvand72@gmail.com] (f), Zeinab Ojani [zeinabojani@gmail.com] (g), Mohammad Zayandeh Ghohpayeh [m_zayandeh@hotmail.com] (h), Mohammad Zamani [md_zamany@yahoo.com] (i,*), Omid Asbaghi [omid.asbaghi@gmail.com] (j,k,**)