I should have said the Study found that consumption of coffee daily (EITHER caf or decaf) helps prevent the onset of Type II Diabetes. This was done in a Scandanavian country where Type II is rare, and those doing the Study think the reason is the very high consumption of coffee, even by children.
Once you have Type II Diabetes, it only helps if your coffee is decaf, of course, since caffeine can play with blood Sugar levels.