The Definition of Glycemia and Why It Matters

Foods that affect blood sugar levels

blood glucose test
Testing blood glucose to find out how food affects blood sugar. Mark Hatfield/E+/Getty Images

Glycemic literally means "causing glucose (sugar) in the blood." Blood glucose levels are closely related to the amount and type of carbohydrates consumed. Glycemia is the related noun meaning glucose or sugar in the blood. High-glycemic foods can cause a rise in blood glucose, which can last for a longer time in the blood. Low-glycemic foods can cause a small blood sugar increase that usually does not last as long.

Glycemic Control and Diabetes

For those who have diabetes, glycemic control is a primary goal. People who are predisposed to getting diabetes, those with metabolic syndrome, insulin resistance or reactive hypoglycemia also have health improvements if blood sugar is more or less stable.

Appetite Control

Another good reason to keep blood sugar stable is appetite control. It has been shown in research studies that people are hungrier when eating high-glycemic carbohydrates compared to eating the same amount of carbs that are less glycemic.

Glycemic Index

Foods with a lot of sugar tend to be very glycemic. Also, starches in foods such as potatoes, bread, and grain products are made of long strings of glucose, so these foods can be as much or even more glycemic than sugary foods. The more processed a food is, the more glycemic it will be. For example, instant oatmeal in packets is more glycemic than quick-cooking oats, which in turn are more glycemic than steel-cut oats.

The glycemic index can give us ideas about which foods will raise blood sugar more. This measure can give us hints about how much a food will raise blood sugar, but there are a lot of variables and are not pinpoint accurate.

Concerns with the glycemic index
Single food items, rather than combinations of foods, can impact blood sugar differently
Does not take into account other variables that affect blood sugar, such as how food is prepared or how much is eaten
Only includes foods that contain carbohydrates
Does not rank foods based on nutrient content, such as foods low on the index may be high in calories, sugar or saturated fat.


It can be difficult to follow the glycemic index. For one thing, there is no standard for what is considered low-, moderate- and high-glycemic foods. Packaged foods do not list their glycemic ranking on the label, and it can be hard to estimate what it might be.

Basic principles of healthy eating, portion control, and counting carbohydrates are all ways to help you better manage and control your blood sugar. 

Foods That Rank High and Low on the Glycemic Index

There are glycemic index food lists that can help you learn more about the glycemic index of various foods and discern which foods might be better choices for you. The following table has examples of foods that rank high and low on the glycemic index.

High Glycemic FoodsLow Glycemic Foods

Potatoes

Parsnips

Rice cakes

Most commercial cereals

Candy

Sugar-sweetened drinks

Dates

Crackers

Cookies

Ripe bananas

Baked goods and other products made with flour

Meats

Eggs

Soy foods

Foods high in fats such as nuts, avocados, and oils

Beans

Barley

Steel-cut oats

Other grains cooked whole

Non-starchy vegetables

Grapefruit

Berries

Sources:

Mayo Clinic. Glycemic Index: What's Behind the Claims. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/glycemic-index-diet/art-20048478

Mayo Clinic. Is the glycemic index useful for controlling blood sugar if you have diabetes? M. Regina Castro, M.D. http://www.mayoclinic.org/diseases-conditions/diabetes/expert-answers/diabetes/faq-20058466

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