Type 2 diabetes is one of the fastest-growing health challenges in the world, but new research suggests that simple, sustainable lifestyle changes can help prevent it.
A major study co-led by Harvard T.H. Chan School of Public Health and Spanish researchers has found that following a Mediterranean diet, combined with modest calorie reduction, regular exercise, and professional weight-loss support, can reduce the risk of developing type 2 diabetes by 31%.
The study, published in the Annals of Internal Medicine, is one of the most comprehensive trials to date linking diet and lifestyle to diabetes prevention.
“We’re facing a global epidemic of diabetes,” said co-author Frank Hu, chair of the Department of Nutrition at Harvard Chan School.
“Our study provides the highest level of evidence that modest, sustained changes in diet and lifestyle could prevent millions of cases worldwide.”
The Mediterranean diet, which emphasizes fruits, vegetables, whole grains, legumes, nuts, and healthy fats such as olive oil, has long been associated with better heart health and improved insulin sensitivity.
It also recommends moderate consumption of lean proteins and dairy, while minimizing red and processed meats.
Previous studies have shown that this eating pattern reduces inflammation and lowers risk factors linked to type 2 diabetes.
To test how these benefits might be enhanced with added lifestyle measures, researchers turned to the PREDIMED-Plus clinical trial, the largest nutrition and lifestyle randomized study in Europe.
More than 4,700 participants between the ages of 55 and 75 were recruited from 23 Spanish universities.
All participants were overweight or obese and had metabolic syndrome, a cluster of conditions that raise the risk of diabetes, but none had diabetes when the study began.
The participants were divided into two groups. The intervention group followed a Mediterranean diet while also reducing daily calories by about 600, engaging in moderate physical activity such as brisk walking and strength exercises, and receiving ongoing professional support for weight management.
The control group followed a Mediterranean diet as well, but without calorie restriction, exercise guidance, or counseling support.
After six years of follow-up, the results were clear. The intervention group had a 31% lower risk of developing type 2 diabetes compared to the control group. They also lost more weight—on average 3.3 kilograms compared to 0.6 kilograms in the control group—and reduced their waist circumference by 3.6 centimeters compared to 0.3 centimeters.
“In practical terms, adding calorie control and physical activity to the Mediterranean diet prevented about three out of every 100 people from developing diabetes,” explained co-author Miguel Martínez-González of the University of Navarra. “That’s a clear, measurable benefit for public health.”
The findings highlight how powerful modest lifestyle changes can be, especially when applied consistently.
Instead of focusing on drastic diets or intense exercise regimens, the study suggests that small, steady steps—like eating balanced meals, walking regularly, and trimming calories—can significantly cut the risk of one of the world’s most common chronic diseases.
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