Are There Good and Bad Carbs for Patients with Diabetes?

New research suggests that for non-diabetic people who follow a healthful diet, the glycemic index may not be very important…

In the new study, researchers examined whether diets that were similar in calories and carbohydrates, but composed of either high or low glycemic foods had different effects on cardiovascular health. They recruited 163 people who were mostly overweight and had high blood pressure, putting them at greater risk of heart disease and type 2 diabetes.

The subjects were rotated through four diets for five weeks at a time, with all of their food provided to them. The researchers devised each diet to be heart healthy, with plenty of fruits, vegetables, beans, fish, poultry, lean meat and grains. Two of the diets were slightly higher in carbs than what the average American eats, and two were slightly lower.

The researchers then altered the types of carbs they contained. The low glycemic diets included whole grain bread and cereal, apples, steel-cut oats, and non-starchy vegetables. The high glycemic diets allowed white bread, carrot and bran muffins, instant rice and instant oatmeal, and sweet snacks like honey, bananas, and apricots in heavy syrup.

The researchers concluded that, “Diets with low glycemic index of dietary carbohydrate, compared with high glycemic index of dietary carbohydrate, did not result in improvements in insulin sensitivity, lipid levels, or systolic blood pressure. In the context of an overall DASH-type diet, using glycemic index to select specific foods may not improve cardiovascular risk factors or insulin resistance.”

Practice Pearls.

• Diets containing low glycemic foods did not lower cholesterol and other heart disease risk factors compared to diets containing mostly high glycemic.
• One of the limitations of the study is that they did not include people with type 2 diabetes.
• Other trials carried out even longer had reached similar results.

Frank M. Sacks. Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity; The OmniCarb Randomized Clinical Trial, JAMA, 2014;312(23):2531-2541. doi:10.1001/jama.2014.16658 Abstract.