A moderate amount of coffee, about three to five cups a day
Data showed that those who consumed a moderate amount of coffee, about three to five cups a day, were at the lowest risk for problems.
A systematic review published in 2005 found that regular coffee consumption was associated with a significantly reduced risk of developing Type 2 diabetes, with the lowest relative risks (about a third reduction) seen in those who drank at least six or seven cups a day. The latest study, published in 2014, used updated data and included 28 studies and more than 1.1 million participants. Again, the more coffee you drank, the less likely you were to have diabetes. This included both caffeinated and decaffeinated coffee.
-- Aaron E. Carroll is a professor of pediatrics at Indiana University School of Medicine