Glycemic Index Education May Lead to Better Diabetes Control

Nine weeks of education about the glycemic index in foods is enough to encourage adults with type 2 diabetes to adopt better dietary habits that result in improvements to their health, suggests recent research published in Public Health Nutrition.

Participants in a clinical trial attended weekly sessions to learn about the potential benefits of low­–glycemic-index foods. After nine weeks, the participants had adopted a lower glycemic-index diet and recorded lower weight, smaller waists, and improved blood sugar levels. When they were tested again another nine weeks later—during which time they received no additional education—the participants had maintained most of those improvements.

The research addresses a controversy in the nutrition community: Some practitioners believe the principles behind maintaining a low–glycemic-index diet are too complicated for average consumers.

“We found that with education, people with diabetes were able to adopt a lower glycemic-index diet. And it had a significant improvement in their weight control and glucose control,” says Carla Miller, senior study author and an associate professor of human nutrition at Ohio State University. “A vast majority of people with diabetes don’t get sufficient education about their condition when they are diagnosed. And yet for many patients, that’s the only time they receive nutrition education. What they really need is continued education and support to help them maintain good control.”

In the study, people with diabetes were randomized to one of two groups. One group immediately participated in the nine-week intervention, and the other group waited for nine weeks before undergoing the same intervention.

The 103 participants who completed the study were between the ages of 40 and 70, had been diagnosed with type 2 diabetes for at least one year, and did not require insulin therapy for diabetes management. For the most part, participants were already doing a good job of controlling their blood glucose levels.

Each group education session lasted between 90 minutes and two hours. Session topics included self-monitoring of food intake and portion sizes, carbohydrate counting, and maintaining behavioral change. Overall, the intervention emphasized selecting lower glycemic-index foods rather than restricting overall carbohydrate intake.

“The emphasis historically has been to control how much carbohydrate people with diabetes eat rather than the type of carbohydrate they choose. And the controversy has been that the glycemic index is so complicated, it’s just another thing that we are asking people to worry about,” Miller says. “And they do have to balance many different variables to get all of these blood parameters under control. That’s another reason they need a lot more education than they receive.”

Researchers collected health measures and diet and physical activity information before and after the intervention period. During the intervention, participants tested their blood glucose levels before and after meals four days per week. To track the participants’ food choices, researchers made periodic unannounced phone calls and asked patients to recall what they had eaten in the previous 24 hours.

After nine weeks of intervention, participants in the first group lost an average of about 5.1 lbs, decreased their waist circumference by 1.1 inches, reduced their body mass index by almost 1 point, and lowered their blood glucose concentration after eating by almost 18 mg/dL. Another nine weeks later, even with no additional intervention, these participants had maintained those health benefits, with the exception of a slight average gain in waist circumference among women.

The participants who waited nine weeks for the intervention recorded similar health improvements after they attended the education sessions. But Miller notes that while they waited, this group also gained weight and recorded expansions of their waists—yet another sign that education can’t start soon enough for many patients with diabetes.

“They had a trajectory of change that was getting worse,” she says. “People with diabetes do need continued support to sustain optimal glycemic control because the disease progresses as they live longer.”

Based on self-reports of food choices, the study showed that participants’ fiber intake improved and they ate less fat. And they did not restrict carbohydrates but instead made different carbohydrate choices.

“We were not putting people on a strict diet. They consumed the same amount of carbohydrate that they normally would but selected lower glycemic-index foods within that carbohydrate allotment,” Miller says. “That addresses another controversy in nutrition. People with diabetes do not have to go on a low-carb diet, which typically is accompanied by a high intake of fat. What these participants ate was closer to [what] the dietary guidelines generally recommend for Americans, with less than 30% of calories coming from fat. The quantity of carbohydrate does matter to some extent, but the type of carbohydrate makes a big difference.”

— Source: The Ohio State University

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