LOS ANGELES — To reduce your risk of developing Type 2 diabetes, new research from Harvard University scientists offers an eye-opening suggestion: Drink more coffee.

In a large epidemiological study, the researchers found that people who increased their coffee consumption by at least one cup per day over a period of years were 11 percent less likely to get Type 2 diabetes compared with people whose coffee-drinking habits didn’t change.

On the flip side, people who dialed back their coffee habit by at least one cup a day were 17 percent more likely to develop Type 2 diabetes.

The study was published Thursday in Diabetologia, the journal of the European Association for the Study of Diabetes. Previous studies have found a correlation between coffee consumption and a lowered risk of Type 2 diabetes, but this was the first study to look at how changes in coffee consumption affect that risk.

“Coffee is pretty fascinating,” said Shilpa Bhupathiraju, a nutritional epidemiologist at the Harvard School of Public Health and the lead author of the paper. “It seems to be associated with a lower risk for many chronic diseases.”

The findings in this study are based on statistical analysis of three long-term and large-scale studies that tracked the diet, lifestyle and medical conditions of more than 120,000 medical professionals over the course of 20 years.


Previous work has shown that chemical compounds in coffee, not the caffeine, are likely responsible for the association between coffee drinking and lower risk of Type 2 diabetes.

“We know that phenolic compounds in coffee improves glucose metabolism in animal models,” Bhupathiraju said. “Coffee is also a really good source of magnesium, which has been associated with a lower risk of Type 2 diabetes.”

If that is the case, drinking more uncaffeinated coffee should be just as effective as drinking more caffeinated coffee in lowering the risk of Type 2 diabetes. In this study, the researchers found that changes in decaffeinated coffee consumption had no statistical effect on risk. That may be because not enough participants made a major change in their decaf coffee drinking, the authors note.

But before you run out to refill your Starbucks card, keep in mind that increasing the amount of coffee you drink is just one part of keeping Type 2 diabetes at bay.

“You can’t get at causality with these studies,” Bhupathiraju said. “You need a healthy body weight, a good diet and a healthy lifestyle. Coffee consumption in the context of all this is associated with a lower risk.”

However, she said that as long as coffee doesn’t make you jittery or keep you from sleeping, there’s no reason you shouldn’t drink up.

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