# Effects of _Gynura bicolor_ on Glycemic Control and Antioxidant Ability in Predicates
## 1 Introduction  
According to The American Diabetes Association (ADA), people whose fasting plasma glucose (FPG) level is 100 to 125 mg/dL were defined as impaired fasting glucose (IFG), or whose 2 h value in the oral glucose tolerance test (OGTT) is 140 to 199 mg/dL were defined as impaired glucose tolerance (IGT), or individuals with glycated hemoglobin (HbA1c) of 5.7-6.4%. People who meet one of three diagnosis criteria were called \"pred diabetes (preDM)\" [1]. Individuals with both IFG and IGT have more severe dysglycemic condition and are especially at high-risk for type 2 diabetes [2]. According to the International Diabetes Federation (IDF), in 2019, three were 463 million people with preDM, and this number is expected to reach 700 million by 2045 [3]. In total, 5-10% of individuals with preDM develop diabetes annually, with up to 70% eventually developing diabetes. Several trials have reported on the risk of diabetes development in preDM individuals after lifestyle and drug-based interventions. PreDM can convert back to normoglycaemia [4, 5]. Under hyperglycemia or IR condition, oxidative stress will be increased and endothelial dysfunction will occur [6]. The endothelium is a key regulator of vascular function [7], when dysfunction will cause inflammation, vasoconstriction, thrombosis and platelet activation, which are linked with atherosclerosis [8]. Evidence from prospective studiessuggest that cardiovascular disease (CVD) may be associated with preDM [9]. Lifestyle intervention includes diet modification, weight reduction or moderate physical activity. Some studies reported that intensive lifestyle interventions such as achieving and maintaining ideal body weight may prevent the progression to type 2 diabetes in IGT or IFG subjects [10]. In the Da Qing trial in China, 577 individuals with IGT were randomized to dietary counseling, increased exercise, diet plus exercise or control (general recommendations). The cumulative 6-year incidence of diabetes was significantly lower in the diet group (43.8%), the exercise group (41.1%) and diet plus exercise group (46.0%) than the control group (67.7%). In a proportional hazards analysis adjusted for differences in baseline BMI and fasting glucose, the diet, exercise, and diet-plus-exercise interventions were associated with 31% (_p_ < 0.03), 46% (_p_ < 0.0005), and 42% (_p_ < 0.005) reductions in risk of developing diabetes, respectively [11]. In a meta-analysis, it was reported that consuming large amounts of vegetables and fruits may reduce the risk of diabetes and associate to inflammation and oxidative stress [12]. [PERSON] reported that diets containing vegetables and fruits, n-3 fatty acids and fiber attenuate the inflammation [13]. Phytochemicals such as vitamin C, vitamin E, carotenoids, phytosterols, anthocyanins and alkaloids showed anti-inflammation and antioxidant effects [14]. Anthocyanins belong to the widespread class of phenolic compounds collectively named flavonoids. Mechanic studies support the beneficial effects of flavonoids, including anthocyanins, on the biomarkers of CVD risk such as NO, inflammation and endothelial dysfunction. The role of anthocyanins in CVD prevention is strongly related to against oxidative damage [15]. Red-purple vegetables are rich in anthocyanins, the common vegetables in Taiwan such as purple-leaved sweet potato, _Gynura bicolor_ (GB) and purple-leaved colesia. GB is widely distributed in Asia and common cuisine in Taiwan. The leaves of GB distinctively show a reddish purple color on the ab axial side and a green color on the adaxial side. _Gynura_ is used as traditional Chinese medicine for treatment of inflammation, fever, hypertension and diabetes [16; 17]. GB has been shown to have antioxidant, anti-inflammatory and anti-hyperglycemic effects [18; 19; 20]. However, limited clinical human studies have examined the effects on glycemic control and antioxidant ability in preDM subjects.