A new study finds that even if you don't lose weight or boost exercise, following a Mediterranean diet can help prevent the onset of Type 2 diabetes.

In the Spanish study, people at risk for heart disease who followed a diet of fruits, vegetables, whole grains, fish, and fats from nuts or olive oil were about 30 per cent less likely to develop diabetes over a four-year period than those who ate a low-fat diet.

The research was a subanalysis of last year's influential PREDIMED study, involving 7,447 subjects at high risk for cardiovascular disease. Researchers from Universidad de Navarra found that subjects who ate a Mediterranean diet had a 30 per cent greater reduction in the risk of heart attack, stroke, or death from cardiovascular disease than those who ate a low-fat diet. The new paper, published this week in the Annals of Internal Medicine, looked at the development of diabetes among 3,541 subjects who didn't have diabetes at the beginning of the study.

Even just adding olive oil to your diet resulted in a health boost, the study suggests. Participants who added fats from extra-virgin olive oil were 40 per cent less likely to develop diabetes during the study compared with those who followed a low-fat diet.

Recent evidence from Harvard Medical School and Brigham and Women's Hospital in Boston also found that middle-aged women who follow a Mediterranean diet may live healthier, longer lives. Scientists evaluated the diets and medical records of 10,670 women and found that after 15 years those women who followed a Mediterranean diet were 40 per cent more likely to survive to age 70 or over without heart disease, diabetes, or other chronic disease.