Glycemic Index

The glycemic index (GI) is a ranking of carbohydrate foods individuals with diabetes use to manage their disease. This ranking is based on the rate carbohydrates affect blood glucose levels relative to glucose or white bread. Generally, the glycemic index is calculated by measuring blood glucose levels following the ingestion of a carbohydrate. This blood glucose value is compared to the blood glucose value acquired following an equal carbohydrate dose of glucose or white bread. Glucose is absorbed into the bloodstream faster than any other carbohydrate, and is thus given the value of 100. Other carbohydrates are given a number relative to glucose. Foods with low GI indices are released into the bloodstream at a slower rate than high GI foods.

A number of factors influence the digestion and absorption rate of food, including ripeness, particle size, the nature of the starch, the degree of processing and preparation, the commercial brand, and the characteristics of the diabetic patient, and these factors naturally affect each food's glycemic index position or rank. In addition, differences exist in the glycemic inde-ces of foods due to the choice of reference food, the timing of blood sampling, or the computational method used to calculate the glycemic index.

GLYCEMIC INDEX OF COMMON FOODS

GI

GI

Serving

(Glucose

(Bread

size

Food item

= 100)

= 100)

(grams or milliliters)

Beverages

Coca Cola, soft drink (Atlanta,

63

90

250 ml

GA, USA)

Apple juice, unsweetened

40

57

250 ml

Orange juice (mean of Canada,

52

74

250 ml

Australia, & USA)

Breads

Bagel, white, frozen (Lender's

72

103

70 g

Bakery, Montreal Canada)

Wonder, enriched white bread

73

105

30 g

Healthy Choice Hearty 7 Grain

55

79

30 g

Wheat bread (Con Agra

Inc., USA)

Dairy Products and Alternatives

Ice cream, regular flavor, not specified

61

87

50 g

(mean of Canada, Italy, & USA)

Milk, full-fat (mean of Italy, Sweden,

27

38

250 g

USA, Australia, and Canada)

Milk, skim (Canada)

32

46

250 g

Fruit and Fruit Products

Apples, raw (mean of Denmark, New

38

52

120 g

Zealand, Canada, USA, and Italy)

Banana, raw (mean of Canada, USA,

52

74

120 g

Italy, Denmark, and South Africa)

Grapefruit, raw (Canada)

25

36

120 g

Pasta and Noodles

Macaroni and cheese, boxed (Kraft

64

92

180 g

General Foods Canada, Inc., Don

Mills, Canada)

Spaghetti, white or type not specified,

44

64

180 g

boiled 10-15 min (mean of Italy,

Sweden, and Canada)

Ravioli, durum wheat flour, meat-filled,

39

56

180 g

boiled (Australia)

Vegetables

Green peas, frozen, boiled (mean of

48

68

80 g

Canada and India)

Carrots, not specified (Canada)

92

131

80 g

Baked potato, without fat

85

121

150 g

(mean of Canada and USA)

SOURCE: Adapted from Foster-Powell et al.

The objectives of diet management in diabetic patients are to reduce hyperglycemia, prevent hypoglycemic episodes, and reduce the risk of complications. For people with diabetes, the glycemic index is a useful tool in planning meals to achieve and maintain glycemic control. Foods with a low glycemic index release sugar gradually into the bloodstream, producing minimal fluctuations in blood glucose. High GI foods, however, are absorbed quickly into the bloodstream causing an escalation in blood glucose levels and increasing the possibility of hyperglycemia. The body compensates for the rise in blood sugar levels with an accompanying increase in insulin, which within a few hours can cause hypoglycemia. As a result, awareness of the glycemic indices of food assists in preventing large variances in blood glucose levels.

Experts disagree regarding the use of the glycemic index in athletes' diets and in exercise performance. Insufficient evidence exists supporting the benefit of low glycemic meals prior to prolonged exercise. Nonetheless, diet: the total daily food intake, or the types of foods eaten hyperglycemia: high level of sugar in the blood hypoglycemic: related to low level of blood sugar insulin: hormone released by the pancreas to regulate level of sugar in the blood glycogen: storage form of sugar diet: the total daily food intake, or the types of foods eaten hormone: molecules produced by one set of cells that influence the function of another set of cells metabolism: the sum total of reactions in a cell or an organism stillbirth: giving birth to a dead fetus miscarriage: loss of a pregnancy cretinism: arrested mental and physical development fortified: altered by addition of vitamins or minerals

An example of grade III (large and visible) goiter. Most cases of goiter in the developing world are due to an iodine deficiency. Unable to meet the body's hormonal needs, the thyroid becomes enlarged to compensate. [© Lester V. Bergman/Corbis. Reproduced by permission.]

a low GI pre-event meal may be beneficial for athletes who respond negatively to carbohydrate-rich foods prior to exercise or who cannot consume carbohydrates during competition. Athletes are advised to consume carbohydrates of moderate to high GI during prolonged exercise to maximize performance, approximately 1 gram per minute of exercise. Following exercise, moderate to high GI foods enhance glycogen storage. see also Carbohydrates; Diabetes Mellitus; Exchange System.

Julie Lager

Bibliography

Burke, Louise M.; Collier, Gregory R.; and Hargreaves, Mark (1998). "Glycemic Index—A New Tool in Sport Nutrition?" International Journal of Sport Nutrition 8:401-415.

Foster-Powell, Kaye; Holt, Susanna H. A.; and Brand-Miller, Janette C. (2002). "International Table of Glycemic Index and Glycemic Load Value." American Journal of Clinical Nutrition 76:5-56.

Gretebeck, Randall J.; Gretebeck, Kimberlee A.; and Tittelbach, Thomas J. (2002). "Glycemic Index of Popular Sport Drinks and Energy Foods." Journal of the American Dietetic Association 102(3):415-416.

Ludwig, David S. (2002). "The Glycemic Index: Physiological Mechanisms Relating to Obesity, Diabetes, and Cardiovascular Disease." Journal of the American Medical Association 287(18):2414-2423.

Willette, Walter; Manson, JoAnn; and Liu, Simin (2002). "Glycemic Index, Glycemic Load, and Risk of Type 2 Diabetes." American Journal of Clinical Nutrition 76 (suppl.):274S-281S.

Wolever, Thomas; Jenkins, David J. A.; Jenkins, Alexandra L.; and Josse, Robert G. (1991). "The Glycemic Index: Methodology and Clinical Importance." American Journal of Clinical Nutrition 54:846-854.

Internet Resources

National Institute of Diabetes and Digestive and Kidney Diseases. "Diabetes." Available from <http://www.niddk.nih.gov>

National Library of Medicine. "Diabetes." Available from <http://medlineplus.gov>

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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