NEW YORK (Reuters Health) – A low-carbohydrate, Mediterranean-style diet is more effective than a conventional low-fat, calorie restricted diet for patients with type II diabetes, according to results of a 4-year randomized trial.

Not only did the Mediterranean diet induce greater weight loss, it also resulted in better glycemic control, delayed the need for oral hypoglycemic therapy, and improved some coronary risk factors, investigators report in the Annals of Internal Medicine for September 1.

Both types of diets are recommended for weight loss in overweight and obese patients with type II diabetes. However, Dr. Dario Giugliano, from the Second University of Naples, Italy, and associates point out, there have been few direct, long-term comparisons between the two.

The 215 patients in their study cohort were newly diagnosed and naïve to hypoglycemic drug therapy. They were 30 to 75 years of age, all with body mass index (BMI) greater than 25 kg/m2 and hemoglobin A1c (HbA1c) levels less than 11%. One hundred eight were randomized to the Mediterranean diet (< 50% of daily calories from carbohydrates), and 107 to a low-fat (< 30% of daily calories from fat). After 4 years, 44% in the Mediterranean diet group and 70% in the low-fat group had HbA1c levels greater than 7% and were receiving hypoglycemic treatment. After 1 year, those in the Mediterranean diet group had lost significantly more weight (absolute difference between groups, -2.0 kg) and experienced greater reductions in BMI (absolute difference, -1 kg/m2), and waist circumference (absolute difference, -1.3 cm). However, differences between groups were not statistically significant at years 3 and 4. Significantly greater increases in high-density lipoprotein cholesterol levels and decreases in triglyceride levels were maintained in the Mediterranean diet group for the duration of the trial. When interpreting these results, Dr. Giugliano’s team cautions that patients and investigators were not blinded to treatment assignment. Nurses and lab staff, however, did not know patients’ group assignments, nor did those who assessed the primary outcome: time to initiation of hypoglycemic therapy. “Perhaps most important,” the investigators conclude, “the findings reinforce the message that benefits of lifestyle interventions should not be overlooked despite the drug-intensive style of medicine fueled by the current medical literature.” Reference:
Ann Intern Med 2009;151:306-314.