Can Glycemic Index Help Control Blood Glucose?

Q: I've read a lot about the concepts of glycemic index and glycemic load. Can they help me control my after-meal blood glucose levels?

A. The use of the glycemic index (GI) and the related concept glycemic load (GL) has long been an area of debate. Currently, the American Diabetes Association (ADA) suggests that GI and GL may be of some value in choosing your foods if you use them in addition to measuring and controlling your total carbohydrate intake.

GI and GL don't provide the whole story about how a food may affect your blood glucose. Other factors on this list play a role:

• your blood glucose at the time you eat
• how much blood glucose-lowering medicine you take, when you take it, and when you eat
• your level of insulin resistance in general and at the time you eat
• the amount of fiber, whole grains, and complex carbohydrates in a food or meal, which can slow the rise of blood glucose
• how ripe a fruit or vegetable is when you eat it -- the riper the food, the more quickly it can raise blood glucose
• the form of the food; for example, fettuccine can affect blood glucose differently than macaroni
• the variety of the food; for example, long grain or short grain rice, Yukon gold or red potatoes, and when and where a product was grown
• whether you eat the food raw or cooked, and how well it is cooked -- the more a food is cooked, the more likely it is to raise blood glucose quickly
• the other foods you eat along with the carbohydrate -- a meal that is mainly carbohydrate with a small amount of fat will raise your blood glucose more quickly than a meal with more fat

Consider using the concepts of glycemic index and glycemic load in conjunction with other healthy eating strategies and priorities. But first and foremost, look at your total carbohydrate count at meals; limit the amount of sweets and sugars you eat; and increase your intake of whole grains, fruits, and vegetables (all of which provide dietary fiber) -- only then should you consider the GI or GL of a food. Don't let GI or GL compromise your goals of eating healthy.

Hope Warshaw, R.D., CDE, is a contributing editor to Diabetic Living and author of Diabetes Meal Planning Made Easy, fourth edition (American Diabetes Association, 2010).

Answer reviewed July 2010