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Glycemic Index

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What is the glycemic index?

The glycemic index (GI) is a rating system for foods that contain carbohydrate. It helps you know how much these foods raise blood sugar.

Carbohydrate raises blood sugar more than other nutrients, like proteins and fats. Some carbohydrate foods raise blood sugar more than others.

  • Low-glycemic foods make blood sugar rise less.
  • High-glycemic foods make blood sugar rise more.

How does it work?

Foods in the index are ranked by number.

  • High glycemic index foods are rated 70 and above.
  • Medium glycemic index foods are 56 to 69.
  • Low glycemic index foods are 55 or less.

What do you need to know about the glycemic index?

Some people who have diabetes use the glycemic index to help them plan meals and manage blood sugar.

  • If you have diabetes, talk with your doctor, a dietitian, or a certified diabetes educator before using a low glycemic index eating plan.
  • Eating low glycemic foods is most helpful when used along with another eating plan for diabetes, such as carbohydrate counting. Counting carbs helps you know how much carbohydrate you're eating. The amount of carbohydrate you eat is more important than the glycemic index of foods in helping you control your blood sugar.
  • The rating of a food can change depending on ripeness, how it is prepared (juiced, mashed, ground), how it is cooked, and how long it is stored.
  • People respond differently to the glycemic content of foods. Many things affect the glycemic index. The only way to know for sure how a food affects your blood sugar is to check your blood sugar before and after you eat that food.
  • High glycemic foods are rarely eaten on their own. This means that the glycemic index might not be helpful unless you're eating a food by itself. Eating foods together can change their rating.


Current as of: March 1, 2023

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
Rhonda O'Brien MS, RD, CDE - Certified Diabetes Educator
Colleen O'Connor PhD, RD - Registered Dietitian