A major European study has found that the Mediterranean diet works significantly better against type 2 diabetes when combined with calorie reduction, regular exercise, and professional weight-loss support. The finding offers a concrete blueprint for disease prevention at a time when diabetes affects hundreds of millions worldwide.
Researchers at the University of Navarra led the PREDIMED-Plus trial, which tracked 4,746 adults aged 55 to 75 over six years. All participants were overweight or obese and had metabolic syndrome, but none had diabetes or heart disease at the start. The study, published in Annals of Internal Medicine, compared two groups: one following a calorie-reduced Mediterranean diet with guided exercise, and another following the traditional Mediterranean approach without restriction or activity coaching.
The results were striking. Those in the structured intervention group were 31% less likely to develop type 2 diabetes than the comparison group. Participants also saw meaningful weight changes: the intervention group lost an average of 3.3 kilograms and reduced waist circumference by 3.6 centimeters, while the control group lost only 0.6 kilograms and trimmed 0.3 centimeters from their waist.
Translating to practical impact, researchers estimated that the program prevented roughly three cases of type 2 diabetes for every 100 participants. For a disease affecting more than 530 million people globally, that prevention rate could prevent thousands of new diagnoses annually if applied widely to at-risk populations.
Miguel Ángel Martínez-González, Professor of Preventive Medicine and Public Health at the University of Navarra and an adjunct professor at Harvard University, emphasized the significance. "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," he said.
The scale of the problem underscores why this matters. Spain has approximately 4.7 million adults with type 2 diabetes, among Europe's highest rates. Across Europe, more than 65 million people are affected, and the United States counts about 38.5 million cases. Type 2 diabetes raises risks of cardiovascular, kidney, and metabolic complications, making prevention essential.
The intervention itself was not extreme. Participants reduced daily calories by about 600 kilocalories, added moderate physical activity like brisk walking and strength training, and received professional guidance. Miguel Ruiz-Canela, first author of the study and professor at the University of Navarra, described it as a practical approach. "It is a tasty, sustainable and culturally accepted approach that offers a practical and effective way to prevent type 2 diabetes," he explained.
Subsequent research from the same trial has strengthened the case. A body composition analysis found that the energy-reduced Mediterranean diet plus physical activity reduced total and visceral fat while slowing age-related muscle loss in older adults. Visceral fat and declining muscle are both linked to cardiometabolic risk, so these changes matter beyond just diabetes prevention.
The broader picture shows Mediterranean diet research consistently supporting cardiovascular benefits. A 2025 review in Cardiovascular Research identified it as one of the best-studied dietary patterns for heart health, citing major randomized trials. Recent analysis from the original PREDIMED study also highlighted the importance of food quality, finding that participants with higher intake of extra virgin olive oil had lower cardiovascular risk than those consuming common olive oil.
An editorial in the same journal by nutrition experts Sharon Herring and Gina Tripicchio praised the trial's clinical importance while raising a practical concern. Bringing this strategy to regions outside the Mediterranean, including the United States, would require addressing barriers like unequal food access, urban environments that discourage activity, and limited access to professional guidance. They argued that public policy changes would be necessary to support such interventions broadly.
The PREDIMED-Plus project, running from 2013 to 2024, involved researchers from more than 200 institutions across Spain's National Health System, with international collaboration from Harvard. Initial funding of over 2 million euros grew to more than 15 million euros, supported primarily by Spain's Carlos III Health Institute and biomedical research networks. The project built on the earlier PREDIMED trial, which found that a Mediterranean diet enriched with extra virgin olive oil or nuts reduced cardiovascular disease risk by 30%.
The findings arrive as pharmaceutical options for obesity and diabetes capture growing attention. PREDIMED-Plus demonstrates that medication is not the only path to meaningful health gains. Sustained lifestyle changes, when properly supported, can still produce major disease prevention.
Author Jessica Williams: "This study proves that preventing diabetes doesn't require a radical overhaul, just structure and support, which makes it far more likely to actually work in the real world."
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