Following a Mediterranean diet rich in olive oil can lower the risk of developing diabetes without having to count calories or boost exercise, according to a new study reported by HealthDay.

A Mediterranean diet emphasizes olive oil, fruits, vegetable, fish and whole grains.

"In the Mediterranean diet, people do end up eating less overall with it, so they probably will end up eating less calories," Lisa Young, an adjunct professor of nutrition at New York University who was not involved with the study, told U.S. News And World Report. "But the nice thing about the Mediterranean diet is that it's high in fiber -- particularly soluble fiber, which is good for [combating] diabetes -- and nuts, which helps to stabilize the blood sugar."

A group of Spanish researchers followed more than 3,500 older adults who were at a high risk of heart disease for four years.

For the study, volunteers were assigned to a Mediterranean diet with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a low-fat diet, which served as the comparison or control diet, HealthDay reported. Those in the olive oil group were allowed a little more than three tablespoons daily. Those in the nut group were allowed about an ounce a day of walnuts, almonds and hazelnuts.

Participants did not get special instructions on losing weight or increasing their physical activity, HealthDay reported.

Researchers found that those who followed the Mediterranean diet supplemented with extra-virgin olive oil saw the greatest risk reduction, at 40 percent. The other Mediterranean diet group also saw a reduced risk by 18 percent; however the result was not "statistically significant," HealthDay reported.

Researchers said the oil's anti-inflammatory and antioxidant properties could be the reason why the extra-virgin olive oil group saw such a reduced risk in diabetes.

HealthDay reports that while the finding shows an association between long-term olive oil consumption and reduced risk of diabetes, it doesn't establish a cause-and-effect relationship.

The research, which was funded by the Spanish government's Institute of Health Carlos III, was recently published online in Annals of Internal Medicine.