High-polyphenol chocolate reduces endothelial dysfunction and oxidative stress during acute transient hyperglycaemia in Type 2 diabetes: a pilot randomized controlled trial

Aims To investigate the effects of high-polyphenol chocolate upon endothelial function and oxidative stress in Type2 diabetes mellitus during acute transient hyperglycaemia induced following a 75-g oral glucose challenge. Methods Ten subjects with Type2 diabetes underwent a double-blinded randomized controlled crossover study. A 75-g oral glucose load was used to induce hyperglycaemia, which was administered to participants 60min after they had ingested either low (control) or high-polyphenol chocolate. Participants undertook testing at weekly intervals, following an initial cocoa-free period. Endothelial function was assessed by both functional [reactive hyperaemia peripheral artery tonometry (EndoPAT-2000) and serum markers (including intercellular adhesion molecule1, P-selectin and P-selectin glycoprotein ligand1]. Urinary 15-F2t-isoprostane adjusted for creatinine was used as an oxidative stress marker. Measurements were made at baseline and 2h post-ingestion of the glucose load. Results Prior consumption of high-polyphenol chocolate before a glucose load improved endothelial function (1.7 +/- 0.1 vs. 2.3 +/- 0.1%, P=0.01), whereas prior consumption of control chocolate resulted in a significant increase in intercellular adhesion molecule1 (321.1 +/- 7.6 vs. 373.6 +/- 10.5ng/ml, P=0.04) and 15-F2t-isoprostane (116.8 +/- 5.7 vs. 207.1 +/- 5.7mg/mol, P=0.02). Analysis of percentage changes from baseline comparing control and high-polyphenol chocolate showed a significant improvement for high-polyphenol chocolate in both measures of endothelial function (P<0.05) and for urinary 15-F2t-isoprostane (P=0.04). Conclusion High-polyphenol chocolate protected against acute hyperglycaemia-induced endothelial dysfunction and oxidative stress in individuals with Type2 diabetes mellitus