Studies show when considering the effect of carbohydrates on blood glucose, it is not just how many carbohydrates you eat but their source as well.1 Some foods cause a quick rise in blood glucose after a meal, while others cause a smaller peak and more gradual decline in blood glucose levels. The measure of how quickly a carbohydrate-containing food raises blood glucose levels is called its glycemic index, or GI.
High-carbohydrate foods are ranked on a scale of 0 to 100, with 100 representing the effect of pure glucose on the body. The lower the GI of a food, the slower the rise in blood glucose. The way the food is cooked (for example, frying vs. baking) can also determine the GI level of the food. The GI breaks foods into 3 levels:2,3
Meats and fats are low in carbohydrates and do not have a GI ranking.
Used in combination with carbohydrate counting, looking at food GI levels may help you stabilize your blood glucose throughout the day. Portion size and total carbohydrate intake are important. High-GI foods may raise blood glucose more quickly, so they are best eaten in moderation and balanced with other foods. Conversely, lower-GI foods may help with blood glucose control, but portion size still matters.
You can choose foods from the low-GI category more often and see if it helps you maintain closer-to-normal blood glucose levels.
1 American Diabetes Association Professional Practice Committee. 5. Facilitating Positive Health Behaviors and Well-being: Standards of Care in Diabetes—2025. Diabetes Care. 2025;48(Suppl. 1). Available at: https://diabetesjournals.org/care/article/48/Supplement_1/S306/157565/1…. Accessed: April 15, 2026.
2 Harvard T.H. Chan School of Public Health. Glycemic Index and Glycemic Load. Available at: https://www.hsph.harvard.edu/nutritionsource/. Accessed: April 15, 2026.
3 Canadian Diabetes Association Glycemic Index
