The Impact of the Mediterranean Diet on Type 2 Diabetes Risk

Main Study Findings

A large clinical study in Spain found that following a Mediterranean diet, combined with moderate calorie reduction, regular physical activity, and professional weight loss support, reduced the risk of developing type 2 diabetes by 31%. This approach proved more effective than the traditional Mediterranean diet without additional lifestyle changes.

Description of the PREDIMED-Plus Study

The PREDIMED-Plus study became the largest nutrition project in Europe, involving the University of Navarra and over 200 researchers from 22 Spanish universities, hospitals, and research centers. The study was conducted in more than 100 primary healthcare centers within Spain’s National Health System. The project began in 2013 after receiving a grant from the European Research Council, with total funding exceeding 15 million euros.

The study included 4,746 adults aged 55 to 75 with overweight or obesity and metabolic syndrome, but without diabetes or cardiovascular disease at the start of the observation. Participants were monitored for six years to assess the effectiveness of different approaches to preventing type 2 diabetes.

Group Comparison

One group followed a Mediterranean diet with reduced calories (about 600 kcal less per day), increased physical activity (such as brisk walking, strength, and balance exercises), and received professional guidance. The control group followed a traditional Mediterranean diet without calorie restriction or physical activity advice.

In the intervention group, the incidence of type 2 diabetes was 31% lower compared to the control group. Participants in this group also lost more weight and reduced their waist circumference more effectively: on average, weight loss was 3.3 kg and waist reduction was 3.6 cm, compared to 0.6 kg and 0.3 cm in the control group, respectively.

Significance for Prevention

The program helped prevent about three cases of type 2 diabetes per 100 participants. This level of prevention could have a significant impact when applied to people at higher risk.

Global Context of Type 2 Diabetes

Type 2 diabetes is one of the fastest-growing chronic diseases worldwide. It is estimated that over 530 million people globally live with diabetes. The increase in cases is linked to urbanization, less healthy diets, sedentary lifestyles, an aging population, and rising rates of overweight and obesity.

In Spain, about 4.7 million adults have diabetes, one of the highest rates in Europe. In the USA, around 38.5 million people are affected, and healthcare costs per patient are among the highest in the world. Type 2 diabetes increases the risk of cardiovascular, kidney, and metabolic complications.

Additional Findings and Research

Body composition analysis published in JAMA Network Open showed that a Mediterranean diet with reduced calories and physical activity helps decrease both total and visceral fat, and slows age-related muscle loss in older adults with overweight or obesity and metabolic syndrome. This is important because visceral fat and muscle loss are closely linked to cardiometabolic risk.

Further PREDIMED-Plus studies examined the impact of sedentary behavior on heart health. They found that replacing sitting time with physical activity was associated with favorable changes in cardiac stress biomarkers.

A 2025 review in Cardiovascular Research highlighted the Mediterranean diet as one of the most studied dietary models for preventing cardiovascular diseases, referencing major randomized trials including PREDIMED, PREDIMED-Plus, CORDIOPREV, and the Lyon Diet Heart Study.

A 2026 analysis from the original PREDIMED study emphasized the importance of food quality in the diet. Higher consumption of extra-virgin olive oil was linked to a lower risk of cardiovascular disease compared to regular olive oil.

Practical Application

The updated PREDIMED-Plus strategy can be used by primary care physicians as a sustainable and cost-effective way to prevent type 2 diabetes on a large scale. The intervention does not require extreme diets, but combines familiar foods, moderate physical activity, gradual weight loss, and professional support.

Study Organization

The project involved various institutions across Spain, including universities, hospitals, and research centers, as well as international partners such as the Harvard School of Public Health. Most researchers are affiliated with the CIBEROBN, CIBERESP, or CIBERDEM institutes.

Conclusion

The PREDIMED-Plus study confirms that sustainable lifestyle changes—including a Mediterranean diet with calorie control, physical activity, and professional support—can significantly reduce the risk of developing type 2 diabetes and improve health outcomes in people with overweight and metabolic syndrome.