Increasing coffee consumption may reduce the risk of type 2 diabetes, according to a recent study.

Researchers from Harvard University found that increasing coffee intake to one and a half cups of per day over a four-year period reduces the risk of type 2 diabetes by 11 percent.

Although previous studies have linked coffee and tea consumption with a lower type 2 diabetes risk, little is known about how changes in coffee and tea consumption influence subsequent type 2 diabetes risk. Researchers examined the associations between four-year changes in coffee and tea consumption and risk of type 2 diabetes in the subsequent four years.

"Changes in coffee consumption habits appear to affect diabetes risk in a relatively short amount of time," researchers said in a statement. "Our findings confirm those of prospective studies that higher coffee consumption is associated with a lower type 2 diabetes risk and provide novel evidence that changes in coffee consumption habits are related to diabetes risk."

For the study, researchers used observational data from three large prospective, United States based studies in their analysis: the Nurses' Health Study (female nurses aged 30-55 years, 1986-2006), the NHS II (younger female nurses aged 25-42 years 1991-2007), and the Health Professionals Follow-up Study(male professionals 40-75 years, 1986-2006). Detailed information on diet, lifestyle, medical conditions, and other chronic diseases was collected every two to four years for more than 20 years.

Researchers said the availability of these repeated measures and the long-duration of follow-up allowed them to evaluate four-year changes in coffee and tea intake in relation to risk of type 2 diabetes in the following four years.

They also examined whether the association with diabetes incidence differed between changes in caffeinated and decaffeinated coffee.

They found that those with highest coffee consumption - at least three cups or more per day - and who maintained that consumption, had the lowest risk of type 2 diabetes. Their risk was 37 percent lower than those who consumed 1 cup or less per day.

Researchers said the changes in risk were observed for caffeinated, but not decaffeinated coffee, and were independent of initial coffee consumption and 4-year changes in other dietary and lifestyle factors.

The findings were recently published in Diabetologia, the journal of the European Association for the Study of Diabetes.