Research shows that a Mediterranean-style diet and diets low in available carbohydrates can offer protection against type 2 diabetes. From a total of 22,295 participants, actively followed up for just over 11 years, 2,330 cases of type 2 diabetes were recorded. To evaluate dietary habits, all individuals completed a list of questions, and the scientists created a 10-point MDS (Mediterranean diet score) and a similar scale to determine the available glycaemic load (carbohydrate) of the diet.
Individuals having an MDS of more than 6 were 12 percent less likely to get diabetes than individuals with the lowest MDS of 3 or less. Individuals having the highest available carbohydrate in their diet were 21 percent more likely to get diabetes than individuals with the lowest score. A high MDS in combination with low available carbohydrate reduced the odds of getting diabetes by 20 percent in comparison to a diet low in MDS and high in GL (glycaemic load).
The role of the Mediterranean diet in controlling weight is still debatable, and in the majority of studies from Mediterranean countries the adherence to the Mediterranean diet was unrelated to overweight. This indicates that the protection against diabetes by the Mediterranean diet is not by means of weight control, but by means of a number of dietary characteristics of the Mediterranean diet.
The researchers explain that a specific characteristic of the Mediterranean diet is the usage of extra virgin olive oil which results in a higher monounsaturated to saturated fatty acids ratio. However research has also been inconsistent here. One review of dietary fat and diabetes indicates that replacing trans and saturated fats with unsaturated fats has benefits on insulin sensitivity and is likely to lessen the risk of type 2 diabetes. Then again, in a randomized trial of high-cardiovascular-risk people who were given the Mediterranean diet supplemented with either nuts or free extra virgin olive oil and were compared with people on a low-fat diet, there was no difference in diabetes incidence between the 2 variants of the Mediterranean diet in comparison to the low fat diet group.
With regards to GL, the researchers say that a high GL diet results in rapid rises in blood glucose and insulin levels. The chronically increased insulin demand could sooner or later lead to pancreatic ß cell failure and, consequently, impaired glucose tolerance as well as increased insulin resistance, which is a diabetes predictor. A high dietary GL has also been unfavorably related to glycaemic control in people with diabetes.
The researchers conclude that a low GL diet that also adequately adheres to the principles of the traditional Mediterranean diet could reduce the occurrence of type 2 diabetes.