Your daily coffee habit may be healthier than you think. People who drink three to four cups of coffee a day have a lower risk of developing type 2 diabetes, a new study reports. The researchers also found similar results for devotees of tea and decaffeinated coffee. But they caution that it's too soon to say whether drinking more tea and coffee will actually lower your risk.
What do we know already?
If you have diabetes, you have too much sugar (glucose) in your blood. The most common form is type 2 diabetes, which usually starts after age 40 and is more common in people who are very overweight (obese). If not properly treated, it can damage your blood vessels, increasing your risk of heart attacks and strokes, as well as problems with your kidneys, feet, and eyes.
In recent decades, rates of type 2 diabetes have climbed dramatically, and they show no sign of ebbing. Indeed, by 2025 the number of people with type 2 diabetes worldwide is expected to increase by 65 percent to 380 million people.
Not surprisingly, a lot of research is being done to find ways to reduce people's risk of getting the disease. Some studies have found that people who drink lots of tea or coffee seem less likely to get diabetes. Researchers have now pooled the results of the best of these studies to see what conclusions they can draw.
What does the new study say?
The researchers found that people who drank three to four cups of coffee a day had about a 25 percent lower risk of developing type 2 diabetes than those who drank zero to two cups a day. On average, people's risk decreased by 7 percent with each additional cup of coffee they drank a day.
It didn't seem to matter whether people drank regular coffee or decaf. Those who drank more than three or four cups of decaffeinated coffee per day had a 36 percent lower risk of diabetes than those who drank none. Drinking tea also appeared to have an effect, with those consuming more than three to four cups having an 18 percent lower risk than those who drank none. (The researchers didn't distinguish between types of tea, such as black or green tea.)
We don't yet know why drinking coffee or tea might help protect against type 2 diabetes, but these findings suggest that caffeine content may not be that important. Previous studies have also suggested that other chemicals in tea and coffee may have a direct effect on how the body manages glucose.
How reliable are the findings?
This was a large review of studies, and its findings should be fairly reliable. The researchers looked at 18 studies with nearly 458,000 people in total. And the results from all the studies took into account several factors that might have influenced people's risk of getting type 2 diabetes, such as their age and weight. Even so, this type of study can't tell us for certain that coffee- or tea-drinking reduced people's risk of getting diabetes. It might be a sign that they had a generally healthy lifestyle. For example, they may have drunk tea or coffee instead of sugary soft drinks or alcohol.
The researchers also point out that 80 percent of the people in the studies were white. So we can't be certain that these findings apply to other groups of people as well.
Where does the study come from?
The study was done by researchers in Australia, France, the Netherlands, Scotland, and the US, and it was funded by grants from several research foundations. It was published in the Archives of Internal Medicine, which is owned by the American Medical Association.
What does this mean for me?
If you drink several cups of coffee or tea a day, this study suggests you may have a lower chance of developing diabetes than someone who drinks less. But we can't say for certain that these drinks actually decrease your risk.
What should I do now?
There's no need to change your coffee- or tea-drinking habits based on this study. But you may find that you enjoy your daily cups a bit more.
Although we don't yet know whether coffee- or tea-drinking might lower your risk, other lifestyle changes can make a difference, such as exercising more and losing weight if you're overweight.