- An intervention that combined a low-calorie Mediterranean diet and exercise led to less diabetes incidence in older adults.
- Men had a greater diabetes risk reduction with the intervention than women.
- The study was based in Spain, and the diet may not be as easy to adhere to in the U.S.
Combining physical activity with a reduced-calorie Mediterranean diet led to a lower diabetes incidence in older, at-risk adults, according to a secondary analysis of a Spanish randomized trial.
Among nearly 5,000 adults with metabolic syndrome and overweight or obesity in the PREDIMED-Plus trial, those who followed this intervention had a 31% lower risk for type 2 diabetes over 6 years relative to those who received only ad libitum Mediterranean diet advice (aHR 0.69, 95% CI 0.59-0.82).
This translated to an absolute reduction of 2.6 diabetes cases per 1,000 person-years, with 9.5% versus 12% incidence, Jordi Salas-Salvadó, MD, PhD, of the Universitat Rovira i Virgili in Spain, and colleagues reported in Annals of Internal Medicine.
Consistently a top-rated diet for health, the Mediterranean diet focuses on high intake of plant-based foods, moderate consumption of fish, poultry, and dairy with optional red wine, and low intake of red meats, sweets, and sugar-sweetened beverages. Common foods featured in the diet include extra-virgin olive oil, fruits, vegetables, legumes, nuts, and whole grains.
“The Mediterranean diet, rich in fiber, whole grains, antioxidants, and anti-inflammatory compounds, is known to reduce diabetes risk, even in the absence of weight loss,” Salas-Salvadó and co-authors wrote, although it does also promote weight loss, as seen in PREDIMED-Plus.
“Although there is no ‘one-size-fits-all’ dietary strategy plan for diabetes prevention, the Mediterranean diet’s higher palatability and cultural acceptance could make it a highly sustainable, long-term, weight loss option when combined with moderately reduced energy intake,” said Salas-Salvadó and co-authors. “Clinicians should consider recommending this approach for patients with overweight or obesity, particularly when conventional Mediterranean dietary advice alone has proven insufficient.”
However, Sharon Herring, MD, MPH, and Gina Tripicchio, PhD, MSEd, both of Temple University in Philadelphia, pointed out that this study was conducted solely in Spain, and sticking to this type of diet may be more challenging in countries like the U.S.
“Participants in the study received extra-virgin olive oil to support adherence and retention; in the United States, prices of extra-virgin olive oil have nearly doubled since 2021 due to a combination of factors including climate change, rising production costs, supply chain disruptions, and now tariffs,” they noted in an accompanying editorial. “[T]he large number of dietitian contacts during the study may prove difficult to scale broadly in the United States given challenges with health care access and reimbursement for prevention services.”
For the randomized, parallel-group PREDIMED-Plus trial, 4,746 adults were enrolled across 23 centers between September 2013 to December 2016. Men were between the ages of 55 to 75, and women were 60 to 75. All had a baseline body mass index (BMI) from ≥27 to <40 without cardiovascular disease or diabetes.
Participants had at least three components of metabolic syndrome, which include: waist circumference 80 cm or more in women and 94 cm or more in men, elevated triglycerides (≥150 mg/dL), reduced HDL cholesterol level (<40mg/dL), elevated blood pressure (≥150/85 mm Hg), and elevated fasting glucose (≥100 mg/dL).
The intervention group was told to follow the Mediterranean diet with a 600-calorie deficit, eating 35-40% of calories from fat, 40-45% from carbohydrates, and approximately 20% from protein. The diet was paired with 45 daily minutes on 6 days per week of progressively increased aerobic physical activity, like brisk walking, along with strength exercises 2 days a week and flexibility and balance exercises 3 days a week.
People in the intervention group lost 3.7% of their body weight (-3.3 kg) compared with 0.6% (-0.6 kg) in controls. The intervention group also lost more waist circumference (-3.6 vs -0.3 cm).
In a prespecified subgroup analysis, men had a greater diabetes risk reduction with the intervention than women (P=0.035 for interaction). Interactions for age, educational level, BMI, waist-to-height ratio, and baseline glucose level weren’t significant.
Both groups had a similar increase in use of antihypertensive and lipid-lowering medications. The control group had a greater uptick in antidiabetic drug use (11.7% vs 9.5% at year 6, P=0.018).
Since the intervention consisted of three components, it’s “difficult to disentangle the proportion of benefits due to the changes in each,” the researchers noted.
