Glycemic Index and Glycemic Load-Measures to Identify Individuals With Insulin Resistance

Posted by admin | On: Aug 18 2016

Clinical indexes of insulin resistance (IR) have acquired increasing importance with the development of various treatments that improve endogenous insulin action.

GlycemicIndexDiabetes

Untitled1

 

In the prospective analysis of a cohort of – 36,000 adults followed for 4 years, Hodge et. al found that higher-carbohydrate diets were associated with a lower risk of development of type 2 diabetes. However, the type of carbohydrate was equally important: low-GI carbohydrates reduced the risk, while high-GI carbohydrates increased the risk. Thus, low GI and low GL are not equivalent and produce different clinical outcomes. Because this issue may be confusing to some readers, it is important to clarify the difference between GI and GL. Both the quality and quantity of carbohydrate determines an individual’s glycemic response to a food or meal. By definition, the GI compares equal quantities of available carbohydrate in foods and provides a measure of carbohydrate quality. Available carbohydrate can be calculated by summing the quantity of available sugars, starch, oligosaccharides, and maltodextrins. As defined, the GL is the product of a food’s GI and its total available carbohydrate content: glycemic load = [GI  x  carbohydrate (g)]/100.

Therefore, the GL provides a summary measure of the relative glycemic impact of a “typical” serving of the food. Foods with a GL ≤10 have been classified as low GL, and those with a value ≥20 as high GL. In healthy individuals, stepwise increases in GL have been shown to predict stepwise elevations in postprandial blood glucose and/or insulin levels. It can be seen from the equation that either a low-GI/high-carbohydrate food or a high-GI/low-carbohydrate food can have the same GL. However, while the effects on postprandial glycemia may be similar, there is evidence that the two approaches will have very different metabolic effects, including differences in β-cell function, triglyceride concentrations, free fatty acid levels, and effects on satiety1.

The average GI of 62 common foods derived from multiple studies by different laboratories2

High Carbohydrate foods

GI

High Carbohydrate foods

GI

White wheat bread* 75±2 Brown rice, boiled 68±4
Whole wheat/whole meal bread 74±2 Barley 28±2
Specialty grain bread 53±2 Sweet corn 52±5
Unleavened wheat bread 70±5 Spaghetti, white 49±2
Wheat roti 62±3 Spaghetti, whole meal 48±5
Chapatti 52±4 Rice noodles† 53±7
Corn tortilla 46±4 Udon noodles 55±7
White rice, boiled* 73±4 Couscous† 65±4
Breakfast Cereals
Cornflakes Rice porridge/congee
Wheat flake biscuits Millet porridge
Instant oat porridge Muesli
Fruit and fruit products
Apple, raw† 36±2 Watermelon, raw 76±4
Orange, raw† 43±3 Dates, raw 42±2
Banana, raw† 51±3 Peaches, canned† 43±5
Pineapple, raw 59±8 Strawberry jam/jelly 49±3
Mango, raw† 51±5 Apple juice 41±2
Orange juice 50±2
Vegetables
Potato, boiled 78 ±4 Pumpkin, boiled 64±7
Potato, instant mash 87±3 Plantain/green banana 55±6
Potato, french fries 63±5 Taro/yam, boiled 53±2
Carrots, boiled 39±4 Vegetable soup 48±5
Sweet potato, boiled 63±6
Dairy Products and alternatives
Milk, full fat 39 ±3 Soy milk 34±4
Milk, skim 37±4 Rice milk 86±7
Ice cream 51±3 Yogurt, fruit 41±2
Legumes
Chickpeas 28±9 Lentils 32±5
Kidney beans 24±4 Soya beans 16±1
Snack products      
Chocolate 40±3 Soft drink/soda 59±3
Popcorn 65±5 Rice crackers/crisps 87±2
Potato crisps 56±3
Sugar
Fructose 15±4 Glucose 103±3
Sucrose 65±4 Honey 61±3

 

Because the glycemic response varies substantially between different foods and because this variability is not explainable by glucose chain length3, 4, the concept of glycemic index was developed to quantify the glycemic responses induced by carbohydrates in different foods. In prospective cohort studies, higher glycemic index and load predicted an increased risk of diabetes in the study5.

Although the exact mechanisms by which high-glycemic index diets may alter the risk of type 2 diabetes are unclear, 2 major pathways have been proposed. First, the same amount of carbohydrates from high-glycemic-index foods, by definition, produce higher blood glucose concentrations and a greater insulin demand than do low-glycemic index foods. It is possible that chronically increased insulin demand results in pancreatic exhaustion that can result in glucose intolerance. Second, high-glycemic-index diets may directly increase insulin resistance. In animal studies, diets high in amylopectin or glucose produced more rapid and severe insulin resistance than did amylose-based diets. Insoluble fiber but not soluble fiber, was found to be inversely associated with diabetes risk in previous cohort studies5.

 

  1. Barclay A W; Glycemic Index, Glycemic Load, and Glycemic Response Are Not the Same, 2005 by the American Diabetes Association.
  2. ATKINSON FS; International Tables of Glycemic Index and Glycemic Load Values: 2008, DIABETES CARE, VOLUME 31, NUMBER 12, DECEMBER 2008.
  3. Wei M, Gibbons LW, Mitchell TL, Kampert JB, Blair SN. Alcohol intake and incidence of type 2 diabetes in men. Diabetes Care 2000; 23: 18–22.
  4. Wannamethee SG, Shaper AG, Perry IJ, Alberti KG. Alcohol consumption and the incidence of type II diabetes. J Epidemiol Community Health 2002; 56:542–8.
  5. Schulze M B et al; Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women. Am J Clin Nutr 2004; 80:348 –5

Leave a comment