insulin pumps

Carbohydrate Counting

Carbohydrate counting is a meal planning method that provides the patient with greater autonomy and flexibility in management of their diet.

The method is based on the total count of carbohydrate consumed in meals and snacks. It is the most appropriate nutritional approach for patients with type I diabetes using the insulin pump or on multiple daily injections because, once the dose of basal insulin is established/set, the patient can adjust/administer insulin based on the content of carbohydrate to be consumed at a given meal. For patients required to take a set amount of insulin at meals the aim should be to maintain a regular daily carbohydrate intake.

Why count carbohydrates?

For two reasons:

1.  Of the three types of nutrients present in foods (carbohydrates, proteins and fats), carbohydrates contribute most to the rise in post-meal blood glucose levels and as a result, are the main factor that determine insulin needs in relation to food intake.

2. Furthermore, equal amounts of carbohydrate, whether of short or long absorption, raise blood sugar in roughly the same way (1 gram of carbohydrate raises blood sugar about 3-5 mg/dl). This means that the quantity rather than the type of carbohydrate plays an important role and is a key factor in determining pre-meal insulin needs.

Therefore, to estimate the amount of insulin needed for a specific meal or snack, one need only count the grams of carbohydrate in the particular food to be consumed.

Once a patient has learned to count carbohydrates it is possible to establish an insulin/carbohydrates ratio on an individual basis. This insulin/carbohydrate ratio can be used to calculate the pre-meal insulin dose.

How much carbohydrate to consume

An exact quantity of carbohydrate cannot be recommended for all patients since meal planning must take into account the individual’s nutritional needs and requirements. Variations in usual intake can be made with the aim of reaching the carbohydrate requirements essential for a healthy diet or to make the diet more appropriate or easier for the patient to follow.

Learning how to count carbohydrates

To become skilled at carbohydrate counting, the patient must learn to:

1. recognize the macronutrients in the diet and their effect on blood glucose;

2. identify which nutrients contain carbohydrates;

3. learn how many carbohydrates are present in a variety of foods; and

4. correctly estimate food portions.

1. Recognizing macronutrients in the diet…

Nutrients can be divided into three categories – carbohydrates, fats or lipids, and proteins.

Carbohydrates, or glucose, contain 4 calories per gram and the resulting energy can be rapidly absorbed. There are rapid absorption carbohydrates (like sugars) and others that are absorbed at a slower rate. The daily recommended intake of carbohydrate should range from 45-60% of total daily caloric intake with preference being made for carbohydrates that are slowly absorbed. Fats or lipids provide reserve energy (1 g = 9 cal). To prevent overweight and cardiovascular illnesses, fats should not make up more than 35% of total daily caloric intake and should come mainly from vegetable oils. Proteins, containing 4 calories per gram, are essential for the building up and functioning of the organism and can be of animal or vegetable origin. The daily recommended intake of proteins should be from 10-20% of total daily caloric intake.

…and their effect on blood glucose levels

Carbohydrates have an almost immediate effect on blood glucose levels raising them within 15 minutes after the start of a meal. Despite the variations in absorption among different kinds of carbohydrates, almost all carbohydrates consumed (90-100%) are transformed to glucose 2 hours after a meal.

Fats and proteins also convert to very small amounts of glucose but over a longer period of time. To be exact, about 60% of ingested protein gets transformed to glucose 3-4 hours after a meal but since proteins normally make up only 10-20% of total caloric intake, their effect on blood glucose is minimal. A minimal amount of fats consumed converts to glucose (10%) and the effect on blood glucose can be seen about 4-8 hours after a meal.

Therefore, fats and proteins do not have an immediate effect on blood glucose, and as a result, have a minimal effect on insulin requirements. If consumed in large amounts, they can have an effect on blood glucose many hours after a meal, as well as contribute to obesity, cardiovascular illnesses and hypertension.

2. Identifying nutrients that contain carbohydrates

It is commonly thought that the only nutrients that contain carbohydrates are cereals, pasta, and breads and often not realized that legumes, tubers, fruits, milk, commercial drinks and breaded foods also contain carbohydrates.

Furthermore, it should be known that the terms carbohydrate, starch, and sugar stand for essentially the same thing since once these nutrients are consumed, they are converted to glucose. Dietary fiber, not being digestible, should be excluded when counting carbohydrates.

Carbohydrates can be found in cereals or cereal derivatives, legumes, selected vegetables, fruit, milk and dairy products, sweets, beverages, and in some artificial sweeteners. The table below lists foods containing carbohydrates.

Table 1. Foods containing carbohydrates.

Cereals or Ceral Derivatives
Pasta (regular white or whole wheat)
Bread (regular white or whole wheat)
Rice (regular white or whole wheat)
Crackers, bread sticks, dry toast
Corn (kernels, polenta, popcorn, corn flour)
Other cereals (barley, pumpernickel, millet, oatmeal…)
Legumes
Beans, lentils, chick peas, green peas, broad bean (fresh or dried)
Soy (beans or milk)
Vegetables
Potatoes
Vegetables
Fruits
Fresh, dried or in syrup fruit
Milk or Dairy Products
Milk and whole or lowfat yogurt
Sweets
Sweets or pastries
Cookies or ice cream
Marmelade, fruit gelatin
Honey
Beverages
Sweetened beverages
Soft drinks
Fruit juices with or without added sugar
Non alcoholic aperitifs
Alcoholic beverages (sweet wines, beer, liquers, aperitifs)
Sweeteners
Saccharose, glucose, fructose, lactose, maltose, dextrose, maltodextrine, corn syrup

3. Learning carbohydrate content of nutrients

To identify the exact content of carbohydrate in a given food, it is essential to refer to nutritional content tables where grams of carbohydrate per nutrient are provided per 100 gr of food. As these tables can be difficult to interpret, it is best to refer to simplified nutritional tables featuring carbohydrates per 100 gr in frequently consumed foods (see table 2).

Table 2. Grams of carbohydrates per 100 gr of food.

Food Carbohydrate
per 100 gr
Cereals
Rice 81 gr
Pasta 79 gr
Tortellini 50 gr
Pizza 53 gr
White pizza 58 gr
White bread 67 gr
Whole wheat bread 48 gr
Milk bread 48 gr
Bread sticks 68 gr
Crackers 80 gr
Dry breakfast toast 82 gr
Cornflakes 87 gr
Muesli 72 gr
Fruits
Fresh pineapple 10 gr
Peache 6 gr
Kiwi 9 gr
Melon 7 gr
Banana 15 gr
Apple 10 gr
Pear 9 gr
Strawberries 5 gr
Figs 11 gr
Sweetened fruit macedonia 17 gr
Fruit juice 14 gr
Fruit juice without sugar 10 gr
Sugar  
Freshly squeezed orange juice 8 gr
Beverages
Red wine trace
Beer 3.5 gr
Food Carbohydrate
per 100 gr
Milk and dairy products
Lowfat milk 5 gr
Fruit yogurt (sweetened) 13 gr
Fruit yogurt frutta (unsweetened) 6 gr
plain yogurt lowfat 4 gr
Desserts
Apple Strudel 39 gr
Tiramisù 52 gr
Sacher cake 68 gr
Saint Honorè cake 36 gr
Crostata with marmelade 65 gr
Crostata with cream 67 gr
Simple dry biscuits 84 gr
Whole wheat cookies 71 gr
Filled snack 67 gr
Chocolate snack 50 gr
Croissant 58 gr
Cannoli with cream 43 gr
Cream Krapfen 56 gr
Legumes
Fresh beans 23 gr
Dried chick peas 47 gr
Frozen green peas 13 gr
Vegetables
French fries or fried potatoes 30 gr
Lettuce 2 gr
Tomatoes 3 gr
Raw carrots 8 gr

It is also possible to prepare more simple summary tables (the size of a credit card) with carbohydrate counting information. These tables are mean as an aid to help the patient remember. Some people prefer to use tables where foods are placed in groups with portions containing 5, 15, 25 gr of carbohydrate (see below).

Starches:
portions containing 25 gr. carbohydrate
30 gr. dry breakfast toast
30 gr. crackers
35 gr. breadsticks
30 gr. uncooked pasta
30 gr. uncooked rice
40 gr. plain white bread
50 gr. whole wheat bread
150 gr. uncooked potatoes
170 gr. mashed potatoes
80 gr. french fries or fried potatoes
30 gr. flour
120 gr. polenta
30 gr. cornflakes
50 gr. pizza
50 gr. dried legumes
200 gr. frozen green peas
Dairy products:
portions containing 5 gr. carbohydrate
100 gr. milk
1 container of plain yogurt (125 gr)
1/2 container fruit yogurt (125 gr)

Fruits:
portions containing 15 g carbohydrate
100 gr. banana, mandarins, or grapes
150 gr. apple, pear, pineapple, kiwi, prunes, or cherries
200 gr. oranges, apricots, or melon
250 gr. peaches, grapefruit, or berries
300 gr. strawberries
400 gr. watermelon

The exact carbohydrate content can also be found by reading the food labels of a given product which contain the total nutritional information of a given food. Special attention should be paid to portion size and the grams of carbohydrate contained therein.

Example of food label: whole wheat biscuits

Nutritional
information
Per
100 gr
Per biscuit
(10 gr)
Calories 445 Kcal 45 Kcal
Protein 7.5 gr 0.8 gr
Fats (total)
- saturated
- monounsaturated
- poliunsaturated
19.5 gr
8.9 gr
9 gr
2 gr
2 gr
0.9 gr
0.9 gr
0.2 gr
Carbohydrates (total)
- sugars
- starches
60 gr
21 gr
39 gr
6 gr
2.1 gr
3.9 gr
Fiber (total)
- soluble
8.5 gr
2 gr
0.9 gr
0.2 gr

Carbohydrate counting for complex foods

Special attention should be given to foods that contain carbohydrates as part of other nutrients, such as breading, since the amount of carbohydrate must also be counted in the total meal. Some recipes do not explicitly appear to contain carbohydrates but include them as part of the ingredients as may be the case with use of bread, potatoes or flour for cooking meatballs, stuffed vegetables, roasted beef or stuffed chicken. Among these types of dishes, it is worth noting, cannelloni, lasagna and these types of foods that contain “besciamel” (which contains flour). To quantify the total carbohydrate of such dishes, it is best to prepare the recipe at home at least once so that the total amount of carbohydrate in the entire dish used can be calculated, and then divide into individual portions. Once this is done, it is possible to determine how much carbohydrate is present in a given portion.

Accurately estimating portion sizes

When learning to count carbohydrates, it is critical to be able to estimate portion size because if this is incorrect then calculation of carbohydrates will be inaccurate. There is no use knowing that 100 g of bread contain 67 g of carbohydrate if one cannot recognize a 100 g portion of bread. To aid in learning to count carbohydrates it is important to have a kitchen scale (with capacity to weigh up to 2-3 kg with 1-2 g increments) or use liquid measuring cups. Since it is not realistic to always have the kitchen scale on hand, practicing with household kitchen items such as cups, serving spoons, glasses and other utensils can help one to gradually learn to estimate portions regularly consumed. Even if standard sizes measurements for kitchen items such as cups and glasses exist, one should initially weigh or measure the quantity of food that their kitchen item actually holds. One can also practice visually recognizing portion sizes and weights. It is always good idea to learn to estimate the grams of carbohydrate in frequently consumed foods first then move on to more complex or less frequently eaten foods. Furthermore, it is important to be consistent and regular when practicing carbohydrate counting since it can take weeks before one feels they have a handle on this method. There is no doubt that practicing at home will help in estimation of portions of not only home cooked meals but also those consumed in restaurants, pizzerias, at friend’s homes and at fast food restaurants. It is recommended that during the learning phase the patient aim at keeping a set amount of carbohydrate at each meal while practicing inclusion of a variety of food types.

Standard household item quantities
Cup of milk

cc. 250

Cup of tea

cc. 150

Class of water

cc. 200

Wine glass

cc. 100

Teaspoon

gr. 5 of sugar

Soup spoon

gr. 10 of sugar

Serving spoon (full)

cc. 120

Note: the above quantities are based on standard household items
that each patient must verify at home with their own utensils.

Once the weight of the portion has been estimated it can be multiplied by the percentage of carbohydrate of the given food (using the above table) then divided by one hundred. The result is the quantity of carbohydrate contained in a specific portion.

Example:

Nutrient weight (portion) X percentage of carbohydrates : 100 = Carbohydrates in given portion

By adding up the sum of all carbohydrates in a given meal it is possible to get a reasonable estimate of carbohydrates of meal. Refer to example below:

Pasta with tomato sauce 90 gr 90 x 72 : 100 = 64.8
Parmesan cheese 1 teaspoon  
Roasted chicken 120 gr   
French fries/fried potatoes 200 gr 200 x 30 : 100 = 60
Olive oil 1 teaspoon  
Bread 50 gr 50 x 60 : 100 = 30
Red wine 1 glass  
One pear 150 gr 150 x 9 : 100 = 13.5
 Total Carbohydrates 168.3

If standard carbohydrate content tables are used, then the portion size of the given nutrient must be estimated and calculated.

Example:

If a patient consumes 60 gr of white bread, they know that 40 gr contain 25 gr of carbohydrate. To determine how much carbohydrates are in 60 gr they must consider that 60 gr of bread = 1 1/2 portions so the resulting carbohydrate content would be 25+25/2= 37.5 gr.

Other factors to consider

In addition to counting carbohydrates, it is important that the person with diabetes take into account other factors that influence the metabolism of carbohydrates such as fats, fibers, proteins, and the glycemic index of foods. The excessive intake of fats and fibers slows down absorption of carbohydrates and their effect on post meal blood glucose levels. Foods rich in fats can also contribute to insulin resistance 8-16 hours after the meal. Intake of protein beyond the daily recommended amount (10-20%) can also contribute to increases in blood glucose several hours post-meal. For example, dinner consisting of large quantities of different kinds of meats can contribute to high blood glucose the morning after.

Glycemic index

The glycemic index of foods is a number which indicates the effect of the food on post meal blood glucose levels. The number specifically indicates much a given nutrient is capable of raising blood glucose levels using white bread, a carbohydrate that is of rapid absorption, as a point of reference with white bread being given the number 100. Nutrients are assigned a number from 1 to 100 and the higher the number, the quicker that nutrient is digested, absorbed and acts upon blood glucose levels. Table x shows glycemic index of some foods in comparison to white bread. Potatoes, cornflakes, white rice have a high glycemic index and enter the bloodstream as glucose more quickly than legumes, that have a low glycemic index and are absorbed and enter the bloodstream as glucose at a slower rate.

Glycemic index of some foods using white bread as a point of reference for rapid absorption.

To calculate the GI with respect to glucose multiply the amount by 0.73

Glucose 137
Puffed rice 128
Cornflakes  119
Honey 104
Boiled potatoes 104
Carrots 101
Mashed potatoes 100
White bread 100
Gnocchi 95
Pineapple  
Watermelon 93
Pure cane saccharose 92
Ice cream 86
White rice 83
Muesli 80
Banana 77
Chocolate 70
Green peas 68
Grapes 66
Peaches 66
Maccheroni 65
Orange 63
Apple 54
Spaghetti 53
Pear 52
Yogurt (plain) 51
Barley/pumpernickel 48
Lowfat milk 46
Apricots 44
Dried beans 42
Lentils 42
Grapefruit 36
Fructose 32
Cherries 32

Glycemic index only accounts for the type of carbohydrate, not the quantity so it has no influence on the pre-meal insulin dose. For example, fifty grams of carbohydrate in a given nutrient should be calculated into the pre-meal insulin dose regardless of the fact that the glycemic index is 25 or 98. Furthermore, regardless of the grams of carbohydrate consumed and the insulin administered, one should expect higher blood glucose values 1-2 hours after consuming a food with a high glycemic index.

Four to five hours after consuming a meal of low glycemic index, the blood glucose should return to pre-meal levels. To avoid high blood glucose 1-2 hours after a meal, the patient should consume foods with a low glycemic index or add fats or dietary fiber to the meal to slow down absorption and digestion of the consumed food. For patients that are on insulin pump therapy, it is possible to use different kinds of boluses depending on the content of the meal: for meals with a high glycemic index, it is best a standard bolus, for meals with a low glycemic index, it is best a square wave bolus.

The glycemic index is not an exact number since it can vary on an individual basis depending on the amount of fat or protein in the meal, type or quantity of fiber, and the rate or order in which nutrients in a meal are consumed. The fact that some carbohydrates may be eaten raw and others cooked, the geographic area where the food was produced, moment of harvest (ripe versus green fruit) also play a role in determining glycemic index. With experience and self blood glucose testing, patients can learn to recognize their individual blood glucose response to different foods, and thus, their own glycemic index. Patients will be able to learn that small portions of certain foods such as pizza produce an unexpected effect on blood sugar and therefore adjust their insulin dose, portion sizes or increase physical activity to accommodate these foods. While glycemic index does not replace carbohydrate counting it can be used to reach greater blood glucose control.

Glycemic load

The glycemic load is proposed to better predict glycemic response to meals. The glycemic load of a given food can be obtained multiplying the glycemic index by the quantity of carbohydrate contained in a given portion of that food. By adding up the glycemic load of each food in a meal, it is then possible to calculate the glycemic load of the entire meal. Using the “glycemic load” helps to better understand the importance of quantity of carbohydrates. For example, compare 400 gr of grapes with 50 gr of dry breakfast biscuits. Grapes have a glycemic index of about 55, while biscuits have one of about 65. The 400 gr of grapes contain about 60 gr of carbohydrate so the glycemic load is 60x55=3300

The 50 gr of biscuits contain about 35 gr of carbohydrates so their glycemic load is 35x65= 2.275, lower than that of the portion of grapes. This easy example shows how misleading it can be to generalize based only on carbohydrate content and food type and lead to making the assumption, for example, that fruit is always better than biscuits without specifying type and quantity consumed.

Since it is difficult in practice to take into account both glycemic index and quantity of carbohydrate in a given food, the patient is advised to learn to count carbohydrates and then remember that, for example, the same amount of potatoes raise blood glucose more rapidly than, bread, that is absorbed quicker than fruit or legumes.

Application of carbohydrate counting

Once a patient has learned to identify which foods contain carbohydrates, can estimate the content in individual portions, and can manage to maintain this balance within a meal, it is time to learn about insulin/carbohydrate ratios. Insulin/carbohydrate ratios indicate the amount of carbohydrate an individual can metabolize for each unit of insulin administered and allows the patient to adjust pre-meal insulin dose to the amount of carbohydrate to be consumed. In the vast majority of patients, the insulin/carbohydrate ratio is equal to 1 IU of insulin per 10-15 gr of carbohydrate. Such a ratio can vary according to individual body weight, insulin sensitivity, physical activity levels, and presence of other illnesses or chronic conditions.

For this reason, it is advisable that the insulin/carbohydrate ratio is determined by the medical practitioner and on an individual basis. While the ways of determining it vary, if it is to be used for optimal metabolic control, it is advisable to use the same method each time for a given individual.

Advantages of carbohydrate counting

Carbohydrate counting permits the patient to maintain good glycemic control while offering flexibility in the diet and lifestyle. This positive feature is probably the reason that this method is widely accepted by patients with type I diabetes. While the success of this method of meal planning requires commitment on the part of the patient, the rewards in terms of greater flexibility in meal planning and the satisfaction of being able to manage ones diet with regard to good blood glucose control are significant.

Commitment on the part of the patient

The patient that decides to learn carbohydrate counting should be prepared to check blood glucose levels several time a day (before and after meals, mid-morning, mid-afternoon, 3 am), keep a diary of blood glucose levels and food consumed, time consumed, and amount of insulin administered at meal times (the basal normally remains unchanged). These records will permit the dietitian or diabetes specialist to understand if and where the patient has made a mistake, whether it be in insulin dose, food choice or if basal insulin needs need to be altered, as well as if the patient is eating in an unbalanced manner. More importantly, these records will help understand how many grams of carbohydrate are metabolized with 1 unit of insulin.

Risks and disadvantages of carbohydrate counting

There are a number of risks and disadvantages of carbohydrate counting that should be known:

•  correct application of this methods calls for the help of a team of experienced professionals;
the need to skilled in making calculations; and
possible weight gain if fat/protein intake is not monitored.
Daniela Bruttomeso
insulin pumps > carbohydrate counting