Beneficial Effects of Grape Pomace Extract on Hyperglycemia, Dyslipidemia, and Oxidative Stress in Experimental Diabetes Mellitus

Grape pomace, a polyphenol-rich byproduct of wine production, represents a promising source of bioactive compounds for managing diabetes and its complications. This study evaluates the effect of a novel grape pomace extract on carbohydrate and lipid metabolism, and oxidative stress in type 1 diabetes mellitus. Diabetes was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin. Starting on day 14 post-induction, rats received oral grape pomace extract at a dose of 45 mg of polyphenols/kg body weight daily for 14 days. On day 28 of the experiment, blood plasma was collected. One-way ANOVA with post hoc testing revealed a hypoglycemic effect of grape pomace extract, as evidenced by reduced fasting blood glucose and improved postprandial glycemic responses. The extract also ameliorated dyslipidemia, lowering total cholesterol and triglycerides while increasing high-density lipoprotein levels and paraoxonase activity in plasma of diabetic rats. Antioxidant defenses were enhanced, as indicated by elevated superoxide dismutase, catalase, and glutathione peroxidase activities, along with reduced protein carbonyls, TBA-reactive products, and lipofuscin in blood plasma following extract administration. These findings demonstrate the metabolic and antioxidant potential of grape pomace polyphenols, although further investigations are needed to elucidate the underlying molecular mechanisms.