Over a 20-year period, researchers periodically collected detailed information on diet, lifestyle and medical conditions in more than 120,000 participants. They found 7,269 cases of Type 2 diabetes.
After controlling for smoking, age, weight, physical activity, alcohol consumption and a family history of diabetes, they found that people who increased their coffee intake by more than an eight-ounce cup a day in a four-year period had an 11 percent lower risk of diabetes than those whose consumption remained steady. People who decreased their consumption by the same amount had a 17 percent higher risk. The report appears online in Diabetologia.
“It’s not the caffeine,” said the lead author, Shilpa N. Bhupathiraju, a research fellow at Harvard. “We know that. But coffee has a lot of antioxidants and other bioactive compounds” important in glucose metabolism. The effect has been found in previous studies with decaffeinated coffee, she said.
Dr. Bhupathiraju warned that coffee is not a cure-all, and that a healthy diet and lifestyle are still the best protection against diabetes. “If you’re going to eat a doughnut and smoke while having coffee,” she said, “it won’t help.”