The study, published in Diabetologia, analysed data from more than 22,000 people in the Greek arm of the ongoing European Prospective Investigation into Cancer and nutrition (EPIC) study - finding that dietary habits, and in particular adherence to a low carbohydrate or Mediterranean diet were associated with a lower chance of developing diabetes.
Led by Dr Carlo La Vecchia from the Mario Negri Institute of Pharmacological Research, Italy, the study suggests that those who follow a Mediterranean diet were up to 12% less likely to develop diabetes, while those with a high carbohydrate intake (measured as a high glyceamic load) were 21% more likely to develop diabetes than those with the lowest glyceamic load (GL).
"The role of the Mediterranean diet in weight control is still controversial, and in most studies from Mediterranean countries the adherence to the Mediterranean diet was unrelated to overweight," said La Vecchia and his colleagues. "This suggests that the protection of the Mediterranean diet against diabetes is not through weight control, but through several dietary characteristics of the Mediterranean diet. However, this issue is difficult to address in cohort studies because of the lack of information on weight changes during follow-up that are rarely recorded."
"A low GL diet that also adequately adheres to the principles of the traditional Mediterranean diet may reduce the incidence of type 2 diabetes," they added.
The team studied data from a total of 22,295 participants involved in the Greek arm of the EPIC stud who have been actively followed more than 11 years. In that time, they identified 2,330 cases of type 2 diabetes.
To assess dietary habits, all participants completed a questionnaire, and the researchers constructed a 10-point Mediterranean diet score (MDS) and a similar scale to measure the available carbohydrate (or glycaemic load [GL]) of the diet.
Those with an MDS of over 6 were 12% less likely to develop diabetes than those with the lowest MDS of 3 or under, the team said.
Meanwhile, participants with the highest available carbohydrate in their diet were 21% more likely to develop diabetes than those with the lowest.
A high MDS combined with low available carbohydrate reduced the chances of developing diabetes by 20% as compared with a diet low in MDS and high in GL.