Drinking coffee, tea, or decaf, may reduce your risk of diabetes, according to a new analysis of 18 studies including hundreds of thousands of people.
A 2005 research review concluded that people who drank the most coffee were one-third less likely to develop diabetes than those who drank the least. In the years since then, the amount of research on coffee and diabetes risk has more than doubled, while other studies have suggested that tea and decaf coffee may also be preventive.
To update the evidence, researchers from The University of Sydney, Australia analyzed 18 studies on coffee, decaf, and tea and the risk of type 2 diabetes published between 1966 and 2009, including just shy of 458,000 people.
Type 2 diabetes, most often tied to obesity, accounts for 90 percent of all diabetes cases in Canada and is expected to rise over the next decade.
For every additional cup of coffee a person consumed each day, the study's authors found a person's risk of diabetes was reduced by 7 percent. In the six studies that looked at decaf coffee, the researchers found people who consumed more than three or four cups a day were at 36 percent lower risk of diabetes. And in seven studies that examined tea drinking and diabetes risk, people who drank more than three or four cups daily were at 18 percent lower diabetes risk.
It's not possible, however, to say from the current evidence that heavy coffee drinkers (and tea and decaf drinkers) don't have other characteristics that might protect them against developing diabetes, such as eating a healthier diet.
The fact that the effects were seen with decaf as well as coffee and tea suggest that if the effects are real, they aren't just due to caffeine, but may be related to other substances found in these beverages, for example magnesium or naturally occurring antioxidants that slow the release of sugar into the blood after a meal.
SOURCE: Archives of Internal Medicine, December 2009
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