Diabetic Diet: Is Determining Glycemic Load Better Than Counting Carbs?

To count carbs or discount them ‒ the debate continues. Being type 2 insulin dependent, I’m trying to make sense of the differing conclusions of two studies that have been published recently. It’s hard to say what these studies really show ‒ it can get confusing with all the information out there ‒ especially when pilaf (pilao) is on Sunday’s lunch menu!

Dr. Andrea Laurenzi of San Raffaele Vita-Salute University in Milan suggests that diabetes patients may benefit from counting the number of carbohydrates in their diet. In a small study ‒ published online in the America Diabetes Association journal Diabetes Care ‒ the Milan researchers looked at 61 adults on insulin pump therapy and found that those who learned to count carbs had a small reduction in weight and waist size after 6 months. Additionally, they reported gains in quality of life and an improvement in blood sugar levels.

On the other hand, Jiansong Bao at the University of Sydney in Australia, says the number of carbs alone might not be the best way to go. Writing in the American Journal of Clinical Nutrition, he feels that how many carbs you eat might be less important for your blood sugar than your food's glycemic load, a measure that also takes into account how quickly you absorb those carbs.

Dr. Sanjeev Mehta, of the Joslin Diabetes Center and Harvard Medical School in Boston says while Laurenzi’s findings do not prove that carb counting is the answer for people with type 1 diabetes, it is widely recommended that people on insulin try to estimate the carbohydrate content of their meals to help calculate their insulin doses. Indeed, a few other studies too have suggested that carbohydrate counting can help people with type 1 diabetes control their blood sugar levels.

There are books and online resources available for people who are interested in learning how to count carbs. However, some people have difficulty learning or sticking with the method, Mehta noted, and benefit from help from a professional, such as a dietitian or certified diabetes educator.

Mayo Clinic nutritionist Katherine Zeratsky, R.D., L.D. explains counting carbohydrates is a method for controlling the amount of carbohydrates you eat at meals and snacks. This is because they have the greatest impact on your blood sugar. Eating consistent amounts of carbohydrates every day helps you control your blood glucose level.

But carbohydrates aren't the only dietary consideration when you have diabetes. You need to also limit fat and cholesterol and control the number of calories you consume. The best way to do this is to control portion sizes, she says.

“Eating a healthy diet helps you control your diabetes and reduces your risk of diabetes-related conditions, such as heart disease and stroke. So, just because a food contains no carbohydrates doesn't mean that you can eat it in unlimited amounts,” she cautions.

However, Bao claims the so-called glycemic load of a food, which also takes into account how quickly it makes the blood sugar rise, might work better. Foods with soluble fiber, such as apples and rolled oats, typically have a low glycemic index, one of the contributors to glycemic load. Foods with a low glycemic index cause the blood sugar to rise slowly, and so put little pressure on the pancreas to produce insulin.

The glycemic load is calculated by multiplying the amount of carbs in grams per serving by the food's glycemic index divided by 100. (The glycemic index for a variety of foods can be found here.)

The Sydney researchers say their findings also suggest that eating foods with high glycemic loads could be linked to chronic disease like type 2 diabetes ‒ which does not require insulin injections ‒ and heart disease by raising blood sugar and insulin levels.

The researchers took finger-prick blood samples from 10 healthy young people who ate a total of 120 different types of food ‒ all with the same calorie content. They also had two groups of volunteers eat meals with various staples from the Western diet, such as cereal, bread, eggs and steak. And the glycemic load repeatedly trumped the carb count in predicting the blood sugar and insulin rise after a meal.

A Reuters report quotes Dr. Edward J. Boyko ‒ a diabetes expert at the University of Washington in Seattle who wasn't involved in the Sydney study ‒ saying it wasn't certain the findings would hold up in people who aren't completely healthy, adding, long-term effects and other nutrients in the food might also be important for disease risk.

"It would just be speculation whether a dietary change like this would help people with type 2 diabetes." The most important problem, Boyko points out, remains pure and simple overeating. "The excess weight is the main thing we ought to focus on…The simplest message would be, eat less."