28/08/2025 - General information
A study coordinated by the Biomedical Research Networking Center (CIBER) of the Carlos III Health Institute (ISCIII), with the participation of researchers from the Cardiovascular Risk and Nutrition Group at the Hospital del Mar Research Institute, led by Dr. Montse Fitó, confirms that adopting a low-calorie Mediterranean diet along with increased physical activity helps reduce the onset of new cases of type 2 diabetes in overweight individuals at high metabolic risk. The research is published in the Annals of Internal Medicine, the journal of the American College of Physicians.
These findings are supported by the first results of the PREDIMED-Plus study, a Spanish multicenter clinical trial funded with more than 15 million euros through various calls, but mainly supported by ISCIII and the CIBER Consortium. The trial followed thousands of people across Spain for six years.
More than 200 specialists from 23 Spanish universities and research centers have shown, for the first time with solid evidence, that this combined strategy is effective in reducing the risk of developing type 2 diabetes.
Type 2 diabetes, a chronic disease that seriously harms health and quality of life, has increased notably in recent years, in parallel with the obesity epidemic. Therefore, it is essential to promote accessible and sustainable prevention strategies.
The PREDIMED study (PREvención con DIeta MEDiterránea), active for more than two decades, had already shown that a Mediterranean diet supplemented with extra virgin olive oil or nuts reduced diabetes incidence by 30% compared to a low-fat diet. However, this reduction occurred with barely perceptible weight loss.
Building on this knowledge, the PREDIMED-Plus study designed a more intensive lifestyle intervention to assess whether it could provide additional benefits compared to less intensive strategies. This strategy was based on weight loss through a slightly hypocaloric Mediterranean diet - rich in fiber and with a low glycemic index - combined with the promotion of physical activity and behavioral support.
The published study included 4,746 participants aged 55 to 75 years with overweight or obesity and metabolic syndrome, without cardiovascular disease or diabetes at baseline. Participants were randomly assigned (50% probability) to one of two programs: one focused on following the Mediterranean Diet (without promoting physical activity or reducing calories) and another behavioral program aimed at weight loss through a calorie-reduced Mediterranean Diet (planned 600 kcal/day reduction) combined with increased physical activity.
After 6 years of follow-up, participants without diabetes at baseline who were assigned to the intensive intervention group (Mediterranean diet and physical activity) showed greater adherence to the Mediterranean diet, increased physical activity, lost more weight, and required less medication to control glucose after being diagnosed with diabetes
The research team concludes that the foods and nutrients in the Mediterranean diet "act synergistically through different mechanisms involved in type 2 diabetes, such as reducing insulin resistance, inflammation, and oxidative stress. These effects are enhanced by physical activity and weight loss. Moreover, because it is a tasty, sustainable, and culturally accepted diet, it can become an ideal long-term strategy for the prevention of cardiometabolic diseases."
PREDIMED-Plus, one of the largest nutrition and health trials ever conducted in Europe, is a randomized cardiovascular prevention trial based on lifestyle changes. In 2023, Nature Medicine highlighted it among the 11 studies that will change medicine in the coming years, due to its scope and scientific relevance.
Extensive collaboration across Spain
The PREDIMED-Plus study involved researchers from CIBER in three areas: Obesity and Nutrition (CIBEROBN), Epidemiology and Public Health (CIBERESP), and Diabetes and Associated Metabolic Diseases (CIBERDEM).
In addition, numerous research groups from various institutions collaborated, including: Universitat Rovira i Virgili and Institut d'Investigació Sanitària Pere i Virgili (Reus); University of Navarra, IdiSNA and Primary Care, Servicio Navarro de Salud; University of Valencia, Universitat Jaume I and Valencian Department of Health; IMIM-Hospital del Mar-Hospital del Mar Research Institute (HMRIB) and Universitat Autònoma de Barcelona; Miguel Hernández University and UMH-ISABIAL (Alicante); Hospital Son Espases and IdISBa (Palma de Mallorca); University of Málaga and IBIMA; IMIBIC and Hospital Reina Sofía (Córdoba); Hospital Clínic and IDIBAPS (Barcelona); University of Granada; Bioaraba, Osakidetza and UPV/EHU (Vitoria-Gasteiz); University of the Balearic Islands - IUNICS; Hospital Virgen de la Victoria and University of Málaga; University of Las Palmas de Gran Canaria; Institute of Biomedicine (IBIOMED), University of León and León Primary Care (Sacyl); Primary Care Health District of Seville and University of Seville; Fundación Jiménez Díaz University Hospital - IISFJD (Madrid); Bellvitge University Hospital - IDIBELL; San Carlos Clinical Hospital - IdISSC (Madrid); University of Jaén; IMDEA Food Institute. This scientific article also counted on the collaboration of the Harvard T.H. Chan School of Public Health (United States).
Olga Castañer, Albert Goday, Helmut Schröder, and Montse Fitó contributed as authors, and a large number of professionals from the Institute and Hospital del Mar are listed as collaborators for their contribution to the project over the years.
Article reference:
Ruiz-Canela M, Corella D, Martínez-González MÁ, et al. Comparison of an energy-reduced Mediterranean diet and physical activity versus an ad libitum Mediterranean diet in the prevention of type 2 diabetes. A secondary analysis of a randomized controlled trial. Ann Intern Med. 26 August 2025. [Epub ahead of print]. doi:10.7326/ANNALS-25-00388
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