Sufferers of type 2 diabetes, which is sometimes referred to as adult-onset diabetes because it is more common in older patients, do not utilize insulin properly to metabolize food. In addition to age, risk factors for the disease include being overweight and physically inactive. In 2000, a Dutch study suggested that once other risks are accounted for, coffee drinkers may be less likely to develop type 2 diabetes than non-coffee drinkers are, but it did not differentiate between caffeinated and non-caffeinated varieties. In the new work, a group of researchers from Harvard University and Brigham and Women's Hospital in Boston followed some 126,000 people for more than a dozen years. Every few years the participants answered detailed questionnaires that included questions about their java habits. The scientists determined that men who drank more than six cups of caffeinated joe each day had a risk of developing type 2 diabetes that was half that of their peers who did not drink caffeinated coffee. Among women, the risk was 30 percent lower for regular coffee drinkers compared to non-drinkers. The effects for decaf coffee lovers were smaller: a 25 percent risk reduction for men and a 15 percent reduction for women as compared to non-drinkers.
"This is good news for coffee drinkers, however it doesn't mean everyone should run out for a latt," cautions study co-author Frank B. Hu of the Harvard School of Public Health. "We still don't know exactly why coffee is beneficial for diabetes, and more research is clearly needed." For one, caffeine has been shown to raise blood sugar levels in the short-term; the authors note, however, that its long-term effects are not yet well understood. The team suggests that other ingredients in a cup of joe, including antioxidants and magnesium, could contribute to the beneficial effects of the beverage against diabetes.