what you already knew: coffee is good for you
Long-Term Coffee Consumption Significantly Reduces Type 2 Diabetes Risk, press release of Monday, January 05, 2004, Harvard School of Public Health. As always, they don't specify what they mean by "one cup" of "caffeinated coffee". It's like saying "one glass of beer" - it's vague (do you mean a pot of light or a pint of stout?). Coffee varies massively in terms of strength; eg. you idio^H^H^Hpeople who drink instant coffee "for the pick-me-up" are probably getting less caffeine than a can of Coke. People who drink real, brewed coffee are getting substantially larger amounts of caffeine (and whatever else is in coffee).
So anyway, I'll keep drinking coffee, green tea, red wine, beer, scotch and whatever else I like. If some of it is healthy, then sweet. If not, shucks.