NEW YORK (Reuters Health) – Adherence to a Mediterranean diet is associated with a substantially reduced risk of diabetes, according to findings from a large prospective study conducted in Spain and reported in BMJ Online First, posted on May 30th.

The Mediterranean diet is rich in olive oil, fish, and plant-based foods, and low in meat and dairy products. The high fiber content and high ratio of monounsaturated fatty acids to saturated fatty acids is believed to improve insulin sensitivity, but less is known about the diet’s effect on diabetes incidence, lead author Dr. M. A. Martinez-Gonzalez at the University of Navarra in Pamplona and associates explain.

The study cohort included 13,380 university graduates without diabetes who completed a full validated food frequency questionnaire at a baseline evaluation between 1999 and 2005. Based on a 9-point scale, 2253 subjects had a low adherence to the diet (score 0-2), 9604 had moderate adherence (score 3-6), and 1523 had high adherence (score 7-9).

There were 33 cases of new-onset, confirmed type 2 diabetes during 58,918 person-years of follow-up.

High adherence to the diet (score > 6) was associated with an 83% relative reduction in the risk of developing diabetes, the report indicates. According to the research team, a 2-point increase was associated with a 35% relative reduction in the risk, with a significant inverse linear trend in the multivariate analysis (p = 0.04).

“Interestingly,” Dr. Martinez-Gonzalez and colleagues write, “among participants with the highest adherence to the diet, there was a high prevalence of important risk factors for diabetes,” including older age, higher BMI, and family history of diabetes.

The lower incidence of diabetes despite their more adverse risk profile suggests that “the diet might have a substantial potential for prevention,” they maintain. Moreover, “the inverse graded dose-response pattern and the significant inverse trend that we observed also support a causal relation.”

BMJ Online First 2008.