Recommended Diet for Diabetics May Need Changing, Study Suggests

The New York Times reports: People with Type 2 diabetes on a high-fiber diet kept their blood sugar under better control when they ate foods like beans and nuts instead of the recommended whole-grain diet, researchers have found.

Beans and nuts are among foods that only modestly increase blood glucose levels; scientists describe these foods as having a low glycemic index. The new study, which lasted six months, is one of the largest and longest to assess the impact of foods with a low-glycemic index, researchers said.

Participants on the low-glycemic diet also saw significant improvements in cholesterol after six months, with increases in HDL, the so-called “good” cholesterol associated with a reduced risk of heart disease, the study found.

“That’s an important issue today, because there’s a double whammy for people who are diabetic," said Dr. David J. A. Jenkins, lead author of the report and a professor of nutritional sciences at the University of Toronto. "If they’re men, they have twice the risk of heart disease, and if they’re women, they have four times the risk. If you can hit the heart disease to which they’re particularly vulnerable, you may have something useful."

“Pharmaceuticals used to control Type 2 diabetes have not shown the expected benefits in terms of reducing cardiovascular disease,” he added.
The study was published on Tuesday in the Journal of the American Medical Association.

Some 210 patients with Type 2 diabetes were randomly assigned to a low-glycemic diet or a high-cereal, high-fiber diet.

The high-cereal high fiber diet emphasized “brown foods” such as whole-grain bread and breakfast cereal, brown rice and potatoes with the skin on. The low-glycemic diet included beans, peas, lentils, pasta, quickly boiled rice and certain breads, like pumpernickel and rye, as well as oatmeal and oat bran cereals.

Both diets are low in saturated fat and trans fat. Both groups were told to limit their consumption of white flour and to eat five servings of vegetables and three servings of fruit each day.

Participants on the low-glycemic diet saw their hemoglobin A1C levels — a measure of blood glucose levels over recent months — reduced slightly, by 0.5 percent on average, but experienced significant improvements in HDL, which increased by 1.7 milligrams per deciliter of blood on average. Those on the high-cereal diet saw smaller reductions in hemoglobin A1C and slight drops in HDL.

Dietitians who work with people who have Type 2 diabetes said earlier studies had not demonstrated the benefits of low-glycemic index foods as clearly as this report.

“We’ve been telling people to eat whole grains for a long time," said Emmy Suhl, a nutrition and diabetes educator at the Joslin Diabetes Center in Boston. "What this study shows is that it’s not enough to have whole grains. It’s these very specific low-glycemic carbohydrates that do a much better job."

But, she said, following such a diet is complicated, since the glycemic index of a food can change depending on how it is prepared and served. “People tell us again and again that diet is the hardest part of diabetes management,” she added.