Glycemic index and diabetes

Glycemic Index and DiabetesJOKHA AL-JASSASI DIETITIANIBRI POLYCLINIC

Glycemic Index (GI) measures how a carbohydrate-containing food

raises blood glucose. Foods are ranked based on how they compare

to a reference food — either glucose or white bread.

GI ranks Key Low Medium HighGlycemic Index

55 or less 56 -69 70 or higherExamples • 100% stone-

ground whole wheat or pumpernickel bread

• Most fruits,

• Whole wheat,

• Quick oats• Brown, wild

or basmati rice,

• White bread or bagel

• Corn flakes,• Puffed rice,

bran flakes,• Shortgrain

white rice,

Factors Influencing GI Ranking

• Type of starch


Type of Starch

• Absorbs less water• Molecules form tight clumps• Slower rate of digestion

• Absorbs more water• Molecules are more open• Faster rate of digestion

Amylose Amylopectin

Lower GIKidney beans (28)

Higher GIRusset potato (85)


• Type of starch• Physical entrapment


Physical Entrapment

Endosperm

Bran

Germ

Bran acts as a physical barrier that slows down enzymatic activity on the internal starch layer.

Lower GI Pumpernickel bread (50)

Higher GIBagel (72)


• Type of starch• Physical entrapment• Viscosity of fiber


Viscosity of FiberViscous, soluble fibers transform

intestinal contents into gel-like matter that slows down enzymatic activity on starch.Lower GIApple (40)

Higher GICheerios (74)


• Type of starch• Physical entrapment• Viscosity of fiber• Fat and protein content


Fat & Protein ContentFat and protein slow down gastric

emptying, and thus, slows down digestion of starch.Lower GI

Potato chips (54)

Higher GI

Baked potato (85)


• Type of starch• Physical entrapment• Viscosity of fiber• Fat and protein content• Acid content


Acid ContentAcid slows down gastric emptying, and thus, slows down the digestion of starch.Lower GISourdough wheat bread (54)

Higher GIWonder white bread (73)


• Type of starch• Physical entrapment• Viscosity of fiber• Fat and protein content• Acid content• Food processing


Food ProcessingHighly processed foods require

less digestive processing.Lower GIOld fashioned, rolled oats (51)

Higher GIQuick, 1-minute oats (66)


• Type of starch• Physical entrapment• Viscosity of fiber• Fat and protein content• Acid content• Food processing• Cooking


CookingCooking swells starch molecules and softens foods, which speeds up the rate of digestion.Lower GI

Al dente spaghetti – boiled 10 to 15 minutes (44)

Higher GI

Over-cooked spaghetti – boiled 20 minutes (64)

Other Causes of Variability in the Glycemic Index

The particle size of the food

The degree of ripeness

How long the food has been stored

The current meal, or the meal before

The pre-meal BG level The procedure for

measuring GI can vary

from study to study, so GI tables can conflict

Both intra-and interpersonal responses can vary significantly

What are the limitations of using glycemic index?

GI values were determined in studies where volunteers ate portions containing 50 grams of carbohydrate of each test food. 50 grams of carbohydrate from popcorn is ten cups popped, while from white rice is about one cup cooked.

There is a wide variation in values assigned to the same food depending on reference source.

GI values can vary depending on many factors GI values measured the effect of a test food when that food was

eaten alone. The effect of food on blood sugar can vary from person to person. A lower GI value does not necessarily mean the food is a better choice.

E.g a chocolate candy bar vs. 1 cup of brown rice have =GI

glycemic load

The glycemic load (GL) is an equation that takes into account the planned portion size of a food as well as the glycemic index of that food.

GL = GI x CHOg per serving/100

Is believed to better represent the glycemic impact of more typical portions of foods

Low GL = 10 or less Medium GL = 11-19 High GL = 20 or more

Example of GL

Example using white bread, GI = 70 GL of 1sl = 70 X 15g/100 = 10.5 GL of 2sl = 70 X 30g/100 = 21 GL of 3sl = 70 X 45g/100 = 31.5

So even a low GI food can have a high GL if the portion is big enough. And, a high GI food can have a lower GL if the portion is controlled

Because GL is based upon GI, GL values of foods can vary for the same reasons that GI can vary

Pictures of Low/High GI Meals & Snacks

GI = 60 GL = 48 GI = 42 GL = 31

Pictures of Low/High GI Meals & Snacks

GI = 85 GL = 48 GI = 39 GL = 22

Who may be interested in the glycemic index?

People who have diabetes may use GI values as an additional tool for managing blood sugar levels.

GI values can also be used when treating reactive hypoglycemia.

Studies have shown that when eating low GI foods, people tend to snack less, which may be helpful in weight control as well as blood sugar control.

GI & Diabetes

Most GI studies have been conducted using non-diabetic subjects

The measurement of the glycemic response is almost always stopped after 2 hour post-meal

Studies which include subject with diabetes show greater variability in GI response among people with diabetes

The GI is based on a 50 gram load of carbohydrate -which can be very different from a typical portion

Studies demonstrate a small overall improvement in BG control at best 0.27-0.43 % drop in A1c. By contrast, standard Medical Nutritional Therapy has

achieved a 1-2% point drop in A1c.

GI or Carbohydrate Counting? There is no one diet or meal plan that works for everyone

with diabetes. The important thing is to follow a meal plan that is tailored to personal preferences and lifestyle

Research shows that both the amount and the type of carbohydrate in food affect blood glucose levels.

Studies also show that the total amount of carbohydrate in food, in general, is a stronger predictor of blood glucose response than the GI.

Based on the research, for most people with diabetes, the first tool for managing blood glucose is some type of carbohydrate counting.

Combined GI with carbohydrate counting, it may provide an additional benefit for achieving blood glucose goals for individuals who can and want to put extra effort into monitoring their food choices

Meats and fats do have a GI ?

Yes No

Case Study – “Amy”

Before

38 YO administrative assistantMarried, no childrenHeight: 5’7”Weight: 320 lbs.=145kgBMI: 50 (severe obesity)Type 2 DM since age 35A1c: 6.3 (Glucophage 500 mg)BP: 148/90 (Altace 10 mg)

Case Study – Amy’s Before Diet

Breakfast: toasted bagel with cream cheese, 16 oz. orange juice, large coffee with whole milkLunch: 6” roast beef & cheese sub sandwich w/ mayo, 20 oz. diet PepsiSnack: (“all afternoon long”) 13 oz. bag Hershey miniature chocolate barsDinner: ½ box macaroni & cheese (made w/ 2% milk), 3 beef hot dogs on buns, waterSnack: 1 ½ cups ice cream

6250 Kcal: 43% CHO (666g), 11% PRO (173g), 46% fat (321g)

GI = 57 (moderate)GL = 352 (very high)

Case Study – Amy’s After Diet

Breakfast: 2 slices 100% WW toast, 1 Tbsp natural, NSA peanut butter, 1 Tbsp all-fruit jelly, 1 cup fresh strawberries, large coffee w/ skim milkLunch: 4 oz. grilled chicken breast, large green salad with varied fresh vegetables & 2 Tbsp vinaigrette dressing, small boiled sweet potato, orange, diet iced teaSnack: 6 oz. light yogurt, ½ cup cherries (frozen)Dinner: 4 oz. grilled salmon w/ lemon juice, 1 cup pasta w/ 1 cup broccoli rabe, 1 Tbsp olive oil, waterSnack: apple2150 Kcal: 47% CHO (251g), 19% PRO (104g),

34% fat (82g)GI = 39 (low)GL = 61 (low)


Before

3 years later…


After

Weight: 205 lbs=92 kgBMI: 32 (mild obesity)A1c: 5.2BP: 120/60, RHR 47Medications: none.

Referances

Johanna Burani, American Diabetes Association, Southern Regional Conference, Marco Island, Florida, May 26, 2006

UCSF Diabetes Center Resources, http://diabetes.ucsf.edu/sites/diabetes.ucsf.edu/files/PEDS%20Glycemic%20Index.pdf , assessed on 28/10/2016

American diabetes Association, Glycemic Index and Diabetes, http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/understanding-carbohydrates/glycemic-index-and-diabetes.html?referrer=https://www.google.com/ Last Edited: May 14, 2014, accessed on 28/10/2016

Patty Haney, GLYCEMICINDEX: FROM RESEARCH TO PRACTICE,

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Glycemic index and diabetes

Health & Medicine

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