Amy Reeder is a Certified Diabetes Educator with a master’s degree in nutrition from the University of Utah. She has worked in the diabetes field since 2005 and has been a Certified Diabetes Educator since 2007. 

If you pay attention to carbohydrates as part of your treatment plan to manage diabetes, you've probably read about the glycemic index and low-glycemic index diets. But is the glycemic index a tool you should be using?

What is the glycemic index?

In short, the glycemic index gives you information on how foods may affect your blood glucose. It is a system that ranks carbohydrate-rich foods on a scale from one to 100 based on their affect on blood sugar levels. The higher the number of the food, the higher your blood sugar may be after eating that food.

On the scale of one to 100, foods with a high glycemic index are quickly digested and absorbed, causing a rapid rise or spike in blood sugar. These high-glycemic index foods usually, but not always, contain refined carbohydrates and are foods that are highly processed.

Foods with a lower glycemic index are digested and absorbed at a slower rate. As a result, these foods cause a more gradual increase in blood sugar, which is healthier and more manageable.

How to use the glycemic index to inform your food choices

Based on the definitions of high- and low-glycemic index foods, you might think that high-GI foods are “bad,” and low-GI foods are “good.” But that is not always the case. When using the glycemic index as a tool, it is still important to choose a wide variety of foods including fruits and veggies, whole grains, lean proteins, and healthy fats—even when those might sometimes have a higher index.

In general, however, low-GI foods are higher in fiber, protein, and fat. When consumed, low-GI foods provide a feeling of fullness and can help with weight loss. Low-GI foods have also been found to lower glucose and cholesterol levels in people with type 2 diabetes. Additionally, low-GI foods decrease insulin levels and insulin resistance in the body, allowing for better blood sugar control.

Examples of high and low glycemic index foods

High-glycemic index foods include:

Pretzels (83), baked potato without skin (98), bagel or roll (72), cola drink (63), white rice (89), brown rice (50), cornflakes (93), white bread (71), 100 percent whole grain bread (51), plain baguette (95).

Low-glycemic index foods include:

Apples (28), Greek-style yogurt (11), peanuts (7), grapefruit (25), tomato juice (38), hummus (6), wheat tortilla (30), black beans (30), pearled barley (28), prunes (29).

The catch when using the glycemic index in diet planning is that it applies when a food is eaten on an empty stomach, without any other foods in combination. This is not how most of us eat. In any given meal or snack, we enjoy a combination of foods. Add a piece of salmon and a salad to that high-glycemic index baked potato and the protein, fat, and fiber in the salmon and salad will lower the glycemic index of that baked potato. Protein, fat, and fiber slow down the digestion and absorption of the carbohydrates in the baked potato, therefore lowering the glycemic index of it and lowering the rapid increase in blood sugar.

Bottom line: use the glycemic index as a guide to identify foods that will not cause a spike in your blood glucose. Incorporate these foods as part of an overall healthy diet as opposed to feeling pressured to follow a strict “low-glycemic index diet.”

A starter guide and glycemic index food list can be found on the Harvard Health site.

Will you use the glycemic index to inform your food choices? Why or why not?