According to some studies done in Italy, dark chocolate has many of the same benefits as vitamin C helping the body use insulin more effectively.
It is suggested that a decline in endothelial function can lead to insulin resistance, which is results in a reduction of insulin mediated glucose uptake.
Two studies published (Hypertension 2005; 46: 398-405 and American Journal of Clinical Nutrition 2005; 81:611-614) showed that after 15 days of ingesting dark chocolate insulin sensitivity was increased and insulin resistance was decreased significantly.
The study is stemmed from earlier studies that showed the cocoa and dark chocolate polyphenols reduce blood pressure by increasing insulin-dependent nitric oxide bioavailability.
Furthermore, this improvement in insulin sensitivity has been correlated with an improvement in endothelial function, suggesting an association between the two events.
Caffeine in dark chocolate has been shown to reduce insulin sensitivity in healthy individuals (Can. J. Physio. Pharmacol. 2001:79: 559-65) and impair glucose metabolism in type 2 diabetes.
Dark chocolate and insulin sensitivity