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What is the glycemic index and can it help me with my diabetes?

The glycemic index classifies carbohydrate-containing foods according to how quickly they raise your blood sugar level. Foods with a high glycemic index number tend to raise your blood sugar faster and higher than foods with a lower value. Some people use this index to help them select foods—especially carbohydrates—when they plan meals.

Dr. Sheila Campbell, CRNA
Nutrition & Dietetics Specialist

Carbohydrate is the primary dietary component affecting insulin secretion and postprandial blood glucose levels. The effects of various carbohydrates on glucose levels are not explained by their sweetness. The glycemic index (GI) quantifies the blood glucose response various carbohydrates produce. The GI ranks foods from 0 to 100 based on the blood glucose response they produce in comparison to a reference food—either white bread or glucose. GI values are classified as low (55 or less), medium (56-69) or high (70 or more). The higher the GI, the faster a food is digested into glucose and absorbed. Multiple variables affect the GI of a food, including where it was grown, how it was processed and what other foods or drink are consumed along with it.

Replacing high-GI carbohydrates with low-GI alternatives improves blood glucose control. The lower insulin response after eating low-GI foods improves uptake by tissues. Larger intakes of high-GI starches have been associated with insulin resistance and unhealthy blood lipid levels. Replacing high-GI foods with lower-GI alternatives has also been associated with lower risk of heart disease.

Janis Jibrin, MS, RD
Nutrition & Dietetics Specialist

Eating a low-glycemic-index (GI) diet in which most of your carbohydrates have a low or medium GI is proving to be good for your blood sugar and other aspects of your health. There is a small but potentially important blood sugar-lowering benefit to a low-GI diet for people with diabetes.

Another blood-sugar bonus is the second-meal effect. Eating a low-GI breakfast, for example, has a carryover effect, so that the next meal, even if eaten four hours later, will have a lower impact on blood sugar than it normally would.

The benefits don't end there. Following a low-glycemic-index diet may also help you drop some pounds because it's more satisfying for the calories consumed, and it has been linked to lower cholesterol levels, a lower risk of heart disease and improved endurance during exercise.

If you can get your family to eat a low-GI diet along with you, all the better. The long-running Nurses' Health Study found that women eating a low-GI diet cut the risk of developing type 2 diabetes by nearly 60 percent, and a recent update on that study found that eating this way can even help protect those carrying a gene that puts them at high risk for the disease.

The Best Life Guide to Managing Diabetes and Pre-Diabetes

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Michaela Ballmann
Nutrition & Dietetics Specialist

The glycemic index is a numerical scale that shows how a particular food affects blood glucose levels. Foods are classified as “Low GI” with a range of 55 or less, “Medium GI” with a range of 56-69, and “High GI,” with a range of 70 and above. Low GI foods include most foods you would normally consider as being healthful (most fruits and vegetables, whole grains, beans and nuts). These foods allow for a slower release of glucose into the system, which is beneficial for diabetics looking to control their postprandial glucose levels. As you move up the GI scale, the foods tend to be lower in fiber, protein, and fat, and will cause a greater spike in blood glucose levels.

The Glycemic Index can be helpful in deciding what foods to eat to help maintain good blood sugar levels, however, we usually eat a combination of foods at a meal, not one individual food item. The Glycemic Load, I believe, is more helpful when it comes to looking at the total effect of a meal (rather than the foods by themselves) on your glucose levels.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.