What Does Glycemic Mean?

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 cause a larger rise in blood glucose, which can last for a longer time as well. Low-glycemic foods tend to cause small blood sugar rises that don't last as long.

Glycemic Control and Diabetes

For diabetics, glycemic control is a primary goal. Prediabetics and those with metabolic syndrome or insulin resistance also have health improvements if blood sugar is more or less stable, as well as people with reactive hypoglycemia.

Appetite Control

Another good reason to keep blood sugar stable is appetite control. It has been shown that people are hungrier when eating high-glycemic carbohydrate compared to the same amount of carb that is less glycemic.​

Glycemic Index

Obviously, foods with a lot of sugar in them tend to be very glycemic. But people are sometimes surprised to hear that the starches in foods such as potatoes, bread, and grain products are made up of long strings of glucose, so these foods can be as or more glycemic than sugary foods. Also, the more processed a food is, the more glycemic it will be. So, for example, instant oatmeal in the 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 variabilities and they shouldn't be relied on as having anything close to pinpoint accuracy.

The glycemic index may have some benefits, but may be problematic as well.

Concerns include:

  • Single food items, rather than combinations of foods, can impact blood sugar differently.
  • Doesn't consider all variables that affect blood sugar, such as how food is prepared or how much is eaten.
  • Only includes foods that contain carbohydrates.
  • Doesn't rank foods based on nutrient content — foods with a low GI ranking 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 don't 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. 

High- and Low-Glycemic Foods

Examples of High-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.

Examples of Low-Glycemic Foods: Foods high in protein such as meats, eggs, and soy foods, foods high in fats such as nuts, avocados, and oils.  Low-glycemic foods with carbohydrate include beans, barley, steel-cut oats, other grains cooked whole, non-starchy vegetables, grapefruit, and berries.

See the Glycemic Index Food Lists to learn more about the glycemic index of various foods.

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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