A so-called Mediterranean diet -- rich in nuts, whole grains, fruits, vegetables and healthy oils -- reduces the likelihood that patients recently diagnosed with type 2 diabetes will need drugs to lower their blood sugar, a new study found.
Among diabetics who followed the Mediterranean-style diet, only 44 percent required the blood sugar-lowering medicines known as antihyperglycemic drugs, compared to 70 percent of patients who followed the standard, low-fat diet recommended by cardiologists, according to a report in the Sept. 1 edition of the journal Annals of Internal Medicine.
Patients on the Mediterranean-style diet also lost more weight and experienced greater improvements in blood sugar control and coronary risk measures than those on the low-fat diet.
"Compared with a low-fat diet, a low-carbohydrate, Mediterranean-style diet led to more favorable changes in glycemic control and coronary risk factors and delayed the need for antihyperglycemic drug therapy in overweight patients with newly diagnosed type 2 diabetes," wrote Dr. Dario Giugliano of the Second University of Naples and his colleagues in the study.
Despite these findings, the authors suggested that drug therapy would still be a primary weapon in the battle against type 2 diabetes, a disease that is projected to affect 380 million people worldwide by 2025, according to estimates cited in the paper.
The type 2 condition, which typically develops in middle age, occurs when blood sugar levels rise because of a lack of insulin, or the body's inability to use insulin efficiently. It can often be treated with diet and exercise, or with drugs less potent than insulin itself. The question, according to the researchers, is whether and when to use drugs.
"Lifestyle intervention studies have demonstrated large reductions in risk for type 2 diabetes that remain after lifestyle counseling is stopped," the authors wrote.
"Despite this beneficial effect, the American Diabetes Association recommends that patients with newly diagnosed type 2 diabetes be treated with pharmacotherapy as well as lifestyle changes... Lifestyle changes are often inadequate because patients do not lose weight or regain weight or their diabetes worsens independent of weight," they added.
To investigate the difference between two lifestyle therapies, a low-fat diet and a Mediterranean diet, Giugliano and colleagues conducted a randomized trial between Jan. 2004 and Sept. 2008 at the Diabetes Clinic of the Azienda Ospedaliera Universitaria at the Second University of Naples.
The researchers looked at 215 overweight people between the ages of 30 and 75 who were newly diagnosed with type 2 diabetes, and had never been treated with antihyperglycemic drugs.
Half were put on a Mediterranean-style diet that was rich in vegetables, whole grains and so-called healthy fats such as olive oil. Most red meat was replaced with poultry and fish. Women were restricted to 1,500 calories per day and men to 1,800, with the goal of no more than 50 percent of calories from complex carbohydrates. The diet had no less than 30 percent of daily calories from fat.
The other half put on a low-fat diet based on American Heart Association guidelines. The diet was rich in whole grains and restricted fats, sweets and high-fat snacks. Women and men were likewise restricted to 1,500 and 1,800 calories per day, respectively. But unlike the Mediterranean diet group, they received no more than 30 percent of calories from fat and no more than 10 percent of calories from saturated fat.
The participants received dietary advice from nutritionists and dietitians during monthly sessions for the first year and every other month thereafter for the duration of the four-year study.
The patients kept diaries to record their food intake, which the researchers used, along with counseling session attendance records, to assess their adherence to the diet.
These self-reported diet details may have limited the accuracy study since researchers could not directly determine what the patients ate, the authors noted.
Another limitation was that both patients and providers knew to which diet the patients were assigned. Thus, doctors who prescribed diabetes medications to patients knew which diet the patients were on, which could have introduced bias.
"Perhaps most important," the authors wrote, was that "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."