A new study suggests that improving the overall quality of one's diet helps to prevent type 2 diabetes.

The study by researchers at the Harvard School of Public Health, found that those who improved their diet quality index scores by 10 percent over four years - by eating more whole grains, fruits and vegetables, and less sweetened beverages and saturated fats, for example - reduced their risk for type 2 diabetes by about 20 percent, compared to those who made no changes to their diets. Dietary quality was measured using the 110-point Alternate Healthy Eating Index 2010.

The study also examined whether improved diet was a marker of other lifestyle changes, such as weight loss or increased physical activity, or if it could independently reduce a person's risk for developing type 2 diabetes.

"We found that diet was indeed associated with diabetes independent of weight loss and increased physical activity," lead researcher Sylvia Ley, PhD, a post-doctoral fellow at the Harvard School of Public Health said.

"If you improve other lifestyle factors you reduce your risk for type 2 diabetes even more, but improving diet quality alone has significant benefits. This is important because it is often difficult for people to maintain a calorie-restricted diet for a long time. We want them to know if they can improve the overall quality of what they eat - consume less red meat and sugar-sweetened beverages, and more fruits, vegetables and whole grains - they are going to improve their health and reduce their risk for diabetes," she said.

The study also showed that it didn't matter how good or poor a person's diet was when they started out, she said.

The study was presented at the American Diabetes Association's 74th Scientific Sessions.