The third study, based on a report from the long-running Women's Health Study, provided a possible explanation for a lower incidence of type 2 diabetes -- the kind that generally develops later in life -- among coffee drinkers. Researchers compared 359 post-menopausal women newly diagnosed with type 2 diabetes and 359 women without the disease. They found that women who drank four or more cups of caffeinated coffee a day had a 56 percent lower risk of developing the condition than those who did not drink coffee.