Scientists find smarter Mediterranean diet cuts diabetes risk by 31%

Launched in 2013 after the University of Navarra received an advance grant of more than €2 million from the European Research Council (ERC), PREDIMED-Plus is the largest nutritional trial ever conducted in Europe. Between 2014 and 2016, additional institutions joined the effort, bringing total funding to more than €15 million. Most support came from the Carlos III Health Institute (ISCIII) and the Center for Biomedical Research Network (CIBER), through its departments on Obesity Pathophysiology and Nutrition (CIBEROBN), Epidemiology and Public Health (CIBERESP), and Diabetes and Related Metabolic Diseases (CIBERDEM).

The study published in Annals of internal medicineIt followed 4,746 adults aged 55 to 75 years who were overweight or obese and had metabolic syndrome but no previous history of cardiovascular disease or diabetes. Over the course of six years, the researchers compared two groups. One group adopted a low-calorie Mediterranean diet (about 600 fewer calories per day), participated in moderate exercise such as brisk walking and strength and balance training, and received professional counselling. The other group continued to follow a traditional Mediterranean diet without calorie limits or exercise advice.

The results revealed that participants who followed a low-calorie diet and exercise not only reduced their risk of diabetes, but also lost more weight and trimmed more of their waist circumference. On average, they lost 3.3 kg and 3.6 cm from the waist, compared to 0.6 kg and 0.3 cm in the control group. This translated into preventing about three new cases of type 2 diabetes per 100 participants – a meaningful public health benefit.

“Diabetes is the first robust clinical outcome for which we have shown – using the strongest evidence available – that a Mediterranean diet with reduced calories, physical activity and weight loss is a highly effective preventive tool,” said Miguel Angel Martinez Gonzalez, MD, professor of preventive medicine and public health at the University of Navarra, associate professor of nutrition at Harvard University, and one of the project’s principal investigators. “These modest, sustainable lifestyle changes, when applied broadly to at-risk populations, could prevent thousands of new diagnoses each year. We hope to soon show similar evidence for other major public health challenges.”

Type 2 diabetes: a preventable global epidemic

According to the International Diabetes Federation, type 2 diabetes now affects more than 530 million people worldwide. Their rise is fueled by urbanization (unhealthy diets, sedentary lifestyles, decreased physical activity), aging populations, and increasing rates of overweight and obesity. In Spain, an estimated 4.7 million adults live with diabetes – most of them type 2 – giving the country one of the highest rates in Europe, with total cases exceeding 65 million. In the United States, approximately 38.5 million people have diabetes, and the disease carries some of the highest health care costs per patient worldwide. Experts stress that prevention is crucial to slowing this escalating crisis, which significantly increases the risk of heart, kidney and metabolic complications.

“The Mediterranean diet works synergistically to improve insulin sensitivity and reduce inflammation. With PREDIMED-Plus, we have demonstrated that combining calorie control with physical activity enhances these benefits,” explained Miguel Ruiz Canela, professor and head of the Department of Preventive Medicine and Public Health at the University of Navarra’s School of Medicine and first author of the study. “It is a delicious, sustainable and culturally acceptable approach that provides a practical and effective way to prevent type 2 diabetes – a global, largely avoidable disease.”

International importance and support for a realistic and scalable strategy

The Annals of Internal Medicine accompanied the bulletin with an editorial by Sharon J. Herring and Gina L. Tribicchio, nutrition and public health experts at Temple University (Philadelphia, USA). They praised the importance of clinical intervention and its potential as a preventive model for type 2 diabetes. Moreover, they caution that replicating similar strategies outside the Mediterranean context—such as in the United States—requires overcoming structural barriers, including unequal access to healthy foods, limitations of the urban environment, and lack of career guidance. In this scenario, they call for the promotion of public policies that promote more nutritious and more equitable environments. At a time when new drugs against obesity and diabetes are making headlines, PREDIMED-Plus shows that modest, sustainable lifestyle changes can still provide powerful health benefits.

The PREDIMED-Plus (2013-2024) project, which includes different patients, is a continuation of the PREDIMED study (2003-2010). This study showed that a Mediterranean diet rich in extra virgin olive oil or nuts reduces the risk of cardiovascular disease by 30%. The researchers stress that primary care providers can incorporate the new intervention as a sustainable and cost-effective strategy to prevent type 2 diabetes on a large scale.

Participating institutions

The Additional Assembly Trial is an extensive network of investigators from all over Spain. University of Navarra Health (2). IMIM-Hospital del Mar, Miguel Hernández Universidad de la Hospital (Magaga)).

The project also benefited from international collaboration with the Harvard T.H. Chan School of Public Health (USA). Most of the participating researchers belong to the CIBEROBN, CIBERESP or CIBERDEM research networks.