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Diabetes: Carbohydrate (Carb) Counting Meal Plan

What is the carb counting meal plan?

Counting carbohydrates is a food plan that adjusts the insulin dose based on the amount of carbs your child plans to eat.

How is this plan different from other carbohydrate meal plans?

This plan is different from other plans. In this plan, the insulin dosage and carbohydrates are not always the same day to day. This plan is more flexible and is usually started after you are familiar with food choices and insulin.

How does this plan work?

Carbohydrates affect your child's blood sugar more than any other kind of nutrient. Insulin works with carbs to supply energy for the body. The main goal is to balance insulin with the carbs your child eats all through the day.

First, you and your diabetes care provider need to figure out how much insulin your child needs to take in relation to the amount of carbohydrate your child plans to eat. There are 2 ways to figure this out:

Units per carb choice (exchange): Count carbs in portion sizes of 15 grams. This is called a "carb choice" or an exchange. Divide the number of grams of carbs in a food by 15 to determine carb choices. For example, if a container of yogurt with fruit has 45 grams of carbs, it equals 3 carb choices.

Units of insulin are then adjusted at every meal to match the number of carb choices. To use this method, your provider needs to tell you how many units of insulin you need for each carb choice. For example, if your child needs 1 unit of insulin for every carb choice, then for 3 carb choices, he would need 3 units of insulin (1 x 3 = 3).

Units of insulin per carb choice X # of carb choices = units of insulin needed.

I/C ratio: Most people use an Insulin to Carbohydrate ratio (I/C ratio) to figure out how much insulin to use. If you use a ratio, you do not need to convert the number of carbs to carb choices. An example of an I/C ratio is 1 unit of insulin for every 10 grams of carbs eaten.

For example, if you plan to eat 60 grams of carbs and your I/C ratio is 1/10, then you would need 6 units of insulin (60 ÷ 10 = 6 units).

Your dietitian will help you figure out your I/C ratio.

Adjustments to the insulin dose

Changes to the dose may be needed because of planned exercise, blood sugar levels, or other factors that may affect blood sugar (such as illness, stress, or menstrual periods). For example, your child may need less insulin if the blood sugar level is low (below 70 mg/dl or 3.9 mmol/L) or more insulin if the blood sugar is too high (above 200 mg/dl or 11.1 mmol/L). Your dietitian and healthcare provider will give you guidelines for making these adjustments. The insulin dose calculated from the I/C ratio is usually reduced by half if it is given before strenuous exercise or at bedtime.

Which foods have carbohydrates?

Carbs are found in foods such as:

  • Starchy foods (such as breads, cereals, rice, starchy vegetables, and pasta)
  • Fruits
  • Milk and yogurt
  • Sweets

Most vegetables, meats, and fats are not high in carbs. They have less of an effect on blood sugar levels. You can adjust your child's insulin dose based on meats and fats, if needed, after you have learned how to count carbs.

To see a list of carb choices, you can order the booklet Choose Your Foods: Exchange Lists for Diabetes from The American Diabetes Association and the American Dietetic Association. This book lists the carbohydrate content for lots of foods and is very useful. Nutrition labels on food packages also list the grams of carbohydrate in a serving of food.

When should my child take insulin?

In general, your child should take insulin so that it starts working as the blood sugar starts to rise. Sugar is absorbed into the blood about 10 minutes after eating. The peak in blood sugar from food is usually about 60 minutes after eating.

  • Humalog/NovoLog/Apidra: Starts working in 10 minutes. The peak activity of this insulin is 100 minutes after it is taken. Take this insulin 15 to 20 minutes before eating (if blood sugar is above 80 mg/dl or 4.5 mmol/L).
  • Regular insulin: Starts working in 20 to 30 minutes. The peak activity is 2 to 4 hours after taking. Take this insulin 30 to 60 minutes before eating.

Sometimes insulin can be given after eating. (For example, toddlers who may not eat consistently, or children with blood sugar levels less than 70 mg/dl or less than 3.9 mmol/L.) Your child's doctor and dietitian will help you create a schedule for when to take insulin and when to eat.

How do I get started?

  1. Keep a food, insulin, blood sugar level, and exercise record for at least 3 days. The more blood sugar tests you can do before meals and 2 hours after meals, the better the advice your dietitian can give you. It is also important to record all doses of insulin or oral medicines taken.
  2. The dietitian will review the report and work with your provider to decide what your child's Insulin to Carb (I/C) ratio is. Some people can use 1 unit of short acting insulin per 15 grams of carb for all meals and snacks (an I/C ratio of 1/15). Your child's ratio may vary from one time of day to another. For example, a 1/15 ratio for breakfast, a 1/30 ratio for lunch, and a 1/10 ratio for dinner.
  3. Start counting carbs and adjusting the insulin dose accordingly. You need to keep careful records for the first 1 to 2 weeks of:
    • grams of carbohydrates your child eats at each meal or snack
    • insulin dose given
    • when the insulin was given (10 minutes before eating, 15 minutes before eating, etc.)
    • blood sugar levels (especially levels 2 hours after meals when levels should be less than 180 mg/dl or less than 10 mmol/L)
  4. After a week or two, review your records with a dietitian to check if any changes need to be made. If the blood sugar values are not in the desired range, then your child's I/C ratio needs to be changed. If the blood sugar value is always high 2 hours after a meal, more insulin is needed for the grams of carb in the I/C ratio. For example, your child might need to change from an I/C ratio of 1/15 to 1/10.

Abstracted from the book, "Understanding Diabetes," 11th Edition, by H. Peter Chase, MD (available by calling 1-800-695-2873).
Published by RelayHealth.
Last modified: 2010-07-20
Last reviewed: 2010-05-11

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a health care professional.

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