Why the Glycemic Index Isn’t a Helpful Tool and What You Should Do Instead

What is the Glycemic Index?

The Glycemic Index measures how carbohydrate-containing food raises blood glucose (blood sugar) compared to pure glucose (like glucose tabs). You may have seen “glycemic index” or “GI” written on food packaging or mentioned in social media and wondered if this is something that should matter to you as someone living with diabetes. Here are tips on what you need to know.

Is the glycemic index helpful?

The GI ranks foods as high (70 or more), medium (56–69), or low (55 or lower). But there are several reasons this index may not be a helpful tool for people with diabetes: 

• The original GI testing was not done on people with diabetes
• Insulin response can vary for each person
• There many other factors involved that affect your blood glucose:
  • Your glucose level before eating
  • Your glucose trend at the time of eating
  • The amount of fiber in the food
  • The ripeness of the fruit or vegetables you eat
  • How fast or slow you eat
  • If foods are eaten with protein or fat
  • The timing of the last dose of your diabetes medication
• There is also no standard definition of “glycemic index” by the Food and Drug Administration (FDA) to use on food packages 

What does the research and the ADA recommend for use of the glycemic index?

Because of the reasons above, every person may have a different response to the food they eat. In fact, the American Diabetes Association’s Standards of Care in Diabetes does not recommend the use of the GI for people with diabetes. 

What is the best way to manage blood glucose levels with my food choices?

Monitoring what you eat and checking your blood glucose after eating is the best way to see how the food you eat impacts your blood glucose. Healthy eating starts with the Diabetes Plate. Fill half of your nine-inch plate with non-starchy vegetables, one-quarter with lean protein, and one-quarter with quality carbs. Quality carbs with a good source of fiber will help slow down the digestion of the carbs you eat, helping to slow the rise in your blood glucose level. 

Other ways to slow the rise in blood glucose after eating include eating carbs with a source of protein or healthy fat. 

To understand how foods affect your blood glucose: 

1. Check the total grams of carbohydrates on the Nutrition Facts label to know how many carbs you are eating.
2. Check your blood glucose levels before you eat.
3. Check again two hours after eating to see the difference.  

Stay Connected

Want more articles like this? Sign up for Diabetes Food Hub’s e-newsletter for diabetes-friendly articles, ideas, and recipes from the ADA’s Nutrition & Wellness team delivered to your inbox every month.