Increasing intake by more than one cup a day was associated with an 11% lower risk of Type 2 diabetes over the next four years, experts found. Reducing consumption by at least one cup had the opposite effect, raising diabetes risk by 17%.
People drinking three cups or more were 37% less likely to develop Type 2 diabetes than those consuming one cup or less.
The research, involving almost 124,000 people, adds to previous evidence linking coffee drinking and protection from diabetes. Unlike previous research, it only found a positive association with caffeinated coffee, possibly because so few participants drank decaf.
The authors, led by Professor of Nutrition Frank Hu, from the Harvard School of Public Health in the US, wrote in the journal Diabetologia: "The findings of the study … demonstrate change in coffee consumption is associated with both immediate and long-term diabetes risk."