While dark chocolate does reduce the risk of Type 2 Diabetes, the study linked above from Medscape clarifies that the reduced risk is compared to the consumption of milk chocolate. For clarification, this study does not say that eating dark chocolate multiple times a week will keep you from getting diabetes, it says that eating dark chocolate multiple times a week is healthier than eating milk chocolate multiple times a week. The NPR article even states "Don't eat too much!" at the end of the article.