Effects of grape seed extract in Type 2 diabetic subjects at high cardiovascular risk: a double blind randomized placebo controlled trial examining metabolic markers, vascular tone, inflammation, oxidative stress and insulin sensitivity

• Published in: Diabetic medicine 2009-05, Vol.26 (5), p.526-531
• Main Authors: Kar, P., Laight, D., Rooprai, H. K., Shaw, K. M., Cummings, M.
• Format: Article
• Language: English
• Subjects: Aged; Albuminuria; Biological and medical sciences; Biomarkers - metabolism; C-Reactive Protein - metabolism; Cardiovascular Diseases - etiology; Cardiovascular Diseases - metabolism; Diabetes Mellitus, Type 2 - drug therapy; Diabetes Mellitus, Type 2 - metabolism; Diabetes. Impaired glucose tolerance; Double-Blind Method; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Endothelium, Vascular - drug effects; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Feeding. Feeding behavior; Female; flavonoids; Fructosamine - metabolism; Fundamental and applied biological sciences. Psychology; grape seed extract; Grape Seed Extract - pharmacology; Grape Seed Extract - therapeutic use; Humans; inflammation; Insulin Resistance - physiology; Male; Medical sciences; Middle Aged; Obesity - complications; oxidative stress; Oxidative Stress - drug effects; Photoplethysmography; Placebos; Risk Factors; Type 2 diabetes; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2009.02727.x

Objective  Current research has focused upon the potential links between novel markers of vascular risk such as endothelial dysfunction, oxidative stress, inflammation and insulin resistance in the pathogenesis of Type 2 diabetes and its complications. Grape seed extract (GSE), a flavonoid‐rich product, is a potential moderator of these markers. This study aimed to test the hypothesis that GSE may improve these markers in high‐risk cardiovascular subjects with Type 2 diabetes. Research design and methods  Thirty‐two Type 2 diabetes mellitus patients, prescribed diet or oral glucose‐lowering agents, received GSE (600 mg/day) or placebo for 4 weeks in a double‐blinded randomized crossover trial. Markers of endothelial function (measured by photoplethysmography), oxidative stress [total antioxidant status (TAOS), reduced glutathione (GSH)/oxidized glutathione (GSSG)], inflammation [highly sensitive C‐reactive protein (hsCRP), urinary albumin : creatinine ratio), insulin resistance [homeostasis model assessment–insulin resistance (HOMA–IR)] and metabolism (fructosamine, lipid profile) was measured at baseline and after intervention with GSE or placebo. Results  Baseline characteristics (16 male and 16 female): age 61.8 ± 6.36 years; body mass index 30.2 ± 5.92 kg/m2; diabetes duration 5.9 ± 2.14 years. Following GSE (but not placebo), significant changes were noted in fructosamine (282 ± 40.9 vs. 273 ± 50.2 mmol/l; P = 0.0004); whole blood GSH (2359 ± 823 vs. 3595 ± 1051 mmol/l; P