An energy-reduced Mediterranean diet combined with physical activity lowered the incidence of type 2 diabetes in older patients with overweight or obesity and metabolic syndrome, according to findings from a randomized trial.
The trial enrolled 4,746 patients aged 55 to 75 years across 23 centers in Spain. All were free of diabetes at baseline but had excess weight and metabolic syndrome. Patients were randomly assigned to either an intervention group that received an energy-reduced Mediterranean diet with physical activity and behavioral support for weight loss, or a control group advised to follow a traditional Mediterranean diet without calorie restriction.
During a median of 6 years of follow-up, 280 cases of type 2 diabetes were identified in the intervention group compared with 349 in the control group. The absolute risk was 9.5% in the intervention group and 12% in the control group, respectively, corresponding to a 31% lower relative risk among patients in the intervention group.
Patients assigned to the intervention achieved greater adherence to the Mediterranean diet, higher physical activity, and larger reductions in body weight and waist circumference compared with the control group. At year 6, mean weight loss was 3.3 kg in the intervention group vs 0.6 kg in the control group. Mean waist circumference decreased by 3.6 cm in the intervention group vs 0.3 cm in the control group.
“Even modest weight losses can lead to reductions in diabetes risk, consistent with previous studies,” wrote Miguel Ruiz-Canela, PharmD, PhD, of the University of Navarra, Pamplona, Spain, and colleagues. They reported that changes in diet quality, increased activity, and reduced visceral fat likely worked together to lower insulin resistance.
The trial included intensive participant contact, particularly in the first year, with regular dietitian visits and counseling sessions. Both groups received extra-virgin olive oil to support adherence.
Limitations included the single-blind design, reliance on self-reported dietary adherence, and the inability to determine the independent effect of diet, exercise, or weight loss. The study population was limited to older patients in Spain with metabolic syndrome, which may restrict generalizability.
The trial was funded by the Instituto de Salud Carlos III.
Source: Annals of Internal Medicine