Based on information reported in the initial questionnaire, about half of the women (14,224) drank one to three cups of coffee per day; 2,875 drank more than six cups; 5,554 four to five cups; 3,231 less than one cup; and 2,928 none. Over the following 11 years, 1,418 of the women reported on surveys that they had been newly diagnosed with type 2 diabetes. After adjusting the data for some of the other diabetes risk factors, women who drank more than six cups of any type of coffee per day were 22 percent less likely than those who drank no coffee to be diagnosed with diabetes; those who drank more than six cups of decaffeinated coffee per day had a 33 percent reduction in risk compared with those who drank none.
(Arch Intern Med. 2006;166:1311-1316. Available pre-embargo to the media at www.jamamedia.org.)