Green tea and type 2 diabetes mellitus

Tea is the most common beverage throughout the world. Green tea (Camellia sinensis) is full of flavonoids (1). This herbal drug has a lot of polyphenols, catechin epicatechin, epigallocatechin and epigallocatechin-3-gallate. It also contains other composites like saponins, caffeine, tannins, and some vitamins. Several different investigations have indicated that green tea has hypo-cholesterolaemic, antioxidant, antimutagenic and anti-inflammatory actions. This is mostly due to the impact of galic acid and catechin provided in green tea (1,2). Various studies have shown that, amongst the flavonoids that are contained in green tea, polyphenol type of tannins and catechins may be acquired. Among these epicatechin, epicatechin-3-gallate, catechins, epigallocatechin and epigallocatechin-3-gallate are the prevalent types which are consisted in green tea. Epigallocatechin-3-gallate has been revealed to have a preventive and treatment influence on various types of chronic diseases along with its anticancer properties (2-6). Additionally some studies have also shown that catechin presented in green tea inhibits the proliferation of breast cancer cells (6-8). Type 2 diabetes mellitus is the most common and on the rise chronic metabolic disease, globally (3,4). Clinical investigations have detected that in type II diabetic patients, oxidative stress plays an important role in producing the adverse effects of diabetes. Rise in free radicals causes strengthen in peroxidation of lipids and increase in insulin resistance (1-4). Green tea contains flavonoids and various polyphenols which have antiinflammatory and anti-oxidative property (4-6). Recently to find the influence of green tea consumption on metabolic and anthropometric parameters of patients with type II diabetes, Mossavi et al., investigated the possible efficiency of various daily doses of green tea consumption for eight weeks on various anthropometric, metabolic, and oxidative stress biomarkers of diabetic individuals (7). The randomized clinical trial was conducted on 63 type II diabetes patients. They found that consumption of four cups of green tea per day produced a significant decrease in body mass index, body weight, waist circumference and systolic blood pressure (7). Green tea also directed to a 1Medical Plants Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran 2Environmental Health Engineering, Engineering Department, Health Faculty, Isfahan University of Medical Sciences, Isfahan, Iran 3Nour Medical Hospital, Isfahan University of Medical Sciences, Isfahan, Iran 4Young Researchers and Elite Club, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran 5Department of Biostatistics and Epidemiology, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran 6Social Health Determinants Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran 7Department of Physical Education and Sport Sciences, Khorasgan University of Isfahan, Isfahan, Iran 8Department of Nephrology, Isfahan University of Medical Sciences, Isfahan, Iran