Pamplona (Spain), August 25. Eating Mediterranean-style, but with fewer calories, more moderate exercise, and professional support for weight loss, reduces the risk of developing type 2 diabetes by 31%. This is the main finding of PREDIMED-Plus , a large Spanish multicenter clinical trial in which the University of Navarra is participating in collaboration with more than 200 researchers from 22 other Spanish universities, hospitals, and research centers, and conducted in over 100 primary care centers of the Spanish National Health System.
This is the largest European trial on nutrition, initiated in 2013 by the University of Navarra thanks to the award of an Advanced Grant from the European Research Council (ERC) of more than €2 million. Subsequently, between 2014 and 2016, the rest of the institutions joined the trial reaching an overall funding of more than 15 million euros, provided mainly by the Carlos III Health Institute (ISCIII) and the Center for Biomedical Research Network (CIBER) through its areas of Physiopathology of Obesity and Nutrition ( CIBEROBN ), Epidemiology and Public Health ( CIBERESP ) and Diabetes and Associated Metabolic Diseases ( CIBERDEM ).
The study, published in Annals of Internal Medicine , followed 4,746 people aged 55 to 75 years with overweight or obesity and metabolic syndrome, with no history of cardiovascular disease or diabetes, for six years. To evaluate whether an optimized version of the Mediterranean diet could reinforce the prevention of type 2 diabetes, researchers compared two groups: one adopted a calorie-reduced Mediterranean diet (about 600 kcal fewer per day), a moderate exercise plan (brisk walking, strength and balance training), and professional guidance; the other followed the traditional Mediterranean diet, without calorie restriction or exercise advice.
Results show that, beyond reducing diabetes risk, the intervention group lost an average of 3.3 kg and reduced waist circumference by 3.6 cm, compared to just 0.6 kg and 0.3 cm in the control group. In practical terms, this meant preventing approximately three in every 100 participants from developing type 2 diabetes—a significant public health benefit.
"Diabetes is the first solid clinical outcome for which we have shown —using the strongest available evidence —that the Mediterranean diet with calorie reduction, physical activity and weight loss is a highly effective preventive tool," said Miguel Ángel Martínez-González , Professor of Preventive Medicine and Public Health at the University of Navarra, Adjunct Professor of Nutrition at Harvard University , and one of the principal investigators of the project. "Applied at scale in at-risk populations, these modest and sustained lifestyle changes could prevent thousands of new diagnoses every year. We hope soon to show similar evidence for other major public health challenges."
Type 2 Diabetes: A Preventable Global Epidemic
Type 2 diabetes now affects more than 530 million people worldwide, according to the latest data from the International Diabetes Federation . Its rapid growth is driven by urbanisation (unhealthy diets, sedentary lifestyles, reduced physical activity), an ageing population, and rising rates of overweight and obesity. In Spain, where some 4.7 million adults live with diabetes (most of them type 2), the disease has one of the highest rates in Europe, where there are more than 65 million people with diabetes. In the United States, the figure is approximately 38.5 million, and the prevalence far exceeds the global average, with one of the highest healthcare costs per patient worldwide. Experts warn that prevention is essential to curb this public health emergency, which significantly increases the risk of cardiovascular, renal, and metabolic complications.
"The Mediterranean diet acts synergistically to improve insulin sensitivity and reduce inflammation. With PREDIMED-Plus, we demonstrate that combining calorie control and physical activity enhances these benefits," explained Miguel Ruiz-Canela , Professor and Chair of Preventive Medicine and Public Health Department at the University of Navarra's School of Medicine and first author of the study. "It is a tasty, sustainable and culturally accepted approach that offers a practical and effective way to prevent type 2 diabetes—a global disease that is, to a large extent, avoidable."
International Relevance and Support for a Realistic and Scalable Strategy
Annals of Internal Medicine accompanied the publication with an editorial by Sharon J. Herring and Gina L. Tripicchio, nutrition and public health experts at Temple University (Philadelphia, USA). They praised the intervention's clinical relevance and its potential as a preventive model for type 2 diabetes. Furthermore, they warn that replicating similar strategies outside the Mediterranean context—such as in the U.S.—requires overcoming structural barriers, including unequal access to healthy foods, the limitations of the urban environment, and the lack of professional guidance. In this scenario, they advocate strengthening public policies that promote more nutritious and more equitable environments. At a time when new drugs against obesity and diabetes are grabbing headlines, PREDIMED-Plus demonstrates that modest, sustained lifestyle changes can still deliver powerful health benefits.
The PREDIMED-Plus project (2013-2024), which involves different patients, is a continuation of the PREDIMED study (2003-2010). This study demonstrated that following a Mediterranean diet enriched with extra-virgin olive oil or nuts reduces the risk of cardiovascular disease by 30%. Researchers emphasize that primary care providers can integrate the new intervention as a sustainable, cost-efficient strategy to prevent type 2 diabetes on a large scale.
Participating Institutions
The PREDIMED-Plus trial has assembled a broad network of investigators from across Spain. In order of the number of participants, the study included researchers from the following institutions: the University of Navarra and the Navarra Health Service (2 centers), Hospital Clínic de Barcelona (2 centers), University of Valencia, Rovira i Virgili University (Reus), IMIM-Hospital del Mar, Miguel Hernández University (Alicante), Son Espases Hospital (Palma de Mallorca), University of Malaga, Reina Sofía Hospital (Córdoba) and University of Granada. In addition, Bioaraba and the UPV/EHU (Vitoria), the University of the Balearic Islands, the Hospital Virgen de la Victoria (Malaga), the University of Las Palmas de Gran Canaria, the University of Leon, the Primary Health Care District of Seville, the Fundación Jiménez Díaz (Madrid), the Hospital de Bellvitge, the Hospital Clínico San Carlos (Madrid), the University of Jaen, and the IMDEA Food Institute (Madrid) have also participated.
The project also benefited from international collaboration with the Harvard T.H. Chan School of Public Health (USA). Most of the participating researchers are affiliated with the CIBEROBN , CIBERESP , or CIBERDEM research networks.
