Grape seed extract supplementation prevents high-fructose diet-induced insulin resistance in rats by improving insulin and adiponectin signalling pathways.

Recent evidence strongly supports the contention that grape seed extract (GSE) improves hyperglycaemia and hyperinsulinaemia in high-fructose-fed rats. To explore the underlying molecular mechanisms of action, we examined the effects of GSE on the expression of muscle proteins related to the insulin signalling pathway and of mRNA for genes involved in the adiponectin signalling pathway. Compared with rats fed on a normal diet, high-fructose-fed rats developed pathological changes, including insulin resistance, hyperinsulinaemia, hypertriacylglycerolaemia, a low level of plasma adiponectin and a high level of plasma fructosamine.

Preventive effect of grape seed extract against high-fructose diet-induced insulin resistance and oxidative stress in rats.

The purpose of the present study was to investigate the preventive effect of grape seed extract (GSE) on insulin resistance and oxidative stress in rats fed a high-fructose diet. After 8 weeks of the experiment, the fasting plasma glucose, insulin concentrations, and the homeostasis model assessment of basal insulin resistance (HOMA-IR) of rats fed a high-fructose diet supplemented with 1% GSE were significantly lower than that of a high-fructose diet group. In the oral glucose tolerance test, rats fed a high-fructose diet supplemented with 1% GSE had a significantly reduced plasma glucose and insulin concentrations after 15 min of glucose loading, indicating that GSE improved glucose intolerance.