Diabetes: Counting Carbs if You Use Insulin
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Carbohydrate counting is an important skill to help you maintain tight control of your blood sugar (glucose) level when you have diabetes. It gives you the flexibility to eat what you want and increases your sense of control and confidence in managing your diabetes.
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Carbohydrate counting is a recommended method of meal planning for people who have diabetes. It involves matching your insulin dosage to the grams of carbohydrate in the foods you eat to keep your blood sugar level in your target range.
Carbohydrate—the body's main source of glucose—affects blood sugar more than any other nutrient. All forms of carbohydrate increase your blood sugar level. Foods that contain carbohydrate include:
Contrary to what you may have heard, you can eat sugar when you have diabetes. But if foods that contain sugar make up a large part of your diet, you are probably not eating enough of other, more nutritious foods.
Test Your Knowledge
Which of these foods contain carbohydrate?
Wheat bread, rice, peas, and oatmeal
Cheesecake, skim milk, and pears
Counting carbohydrate grams allows you to match insulin to the food you eat every day to keep blood sugar at your target level. This method is effective because carbohydrate is the main nutrient that causes blood sugar to rise after meals, increasing the need for insulin. Carbohydrate turns into glucose within 2 hours after you eat.
If you use an insulin pump or take multiple insulin injections, you need to know how many grams of carbohydrate are in a meal to calculate how much rapid-acting insulin to take before you eat. A pump provides a continuous (also known as basal) rate of insulin throughout the day, but it must be programmed at meals to provide extra insulin to allow for the rise in blood sugar after meals. When you know how much carbohydrate you will eat, you can program extra units, or boluses, of insulin to cover your meals.
You figure out how much insulin to use based on your own insulin-to-carbohydrate ratio. This ratio may be different from one person to another, and even your own ratio may change over time. You and your doctor will calculate the ratio by recording the food you eat and testing your blood sugar after meals.
Test Your Knowledge
Carbohydrate counting helps me know how much insulin I need to take at meals.
To count carbohydrate grams at a meal, you need to know how much carbohydrate is in each type of food, whether it is a slice of bread, a bowl of lettuce, or a tablespoon of salad dressing. Fortunately, nearly all packaged foods have labels that tell you how much total carbohydrate is in a single serving. And you can get carbohydrate guides from diabetes educators and the American Diabetes Association.
To calculate the carbohydrate in food that is not packaged, you will need to know standard portions of carbohydrate foods. Each serving size or standard portion contains about 15 grams of carbohydrate.
When you know the number of grams of carbohydrate in a meal, you can figure out how many units of insulin to take based on your personal insulin-to-carbohydrate ratio.
For example: Your doctor may recommend that you take 1 unit of rapid-acting insulin for every 10 to 15 grams of carbohydrate you eat. So if your meal contains 50 grams of carbohydrate, and if your doctor has decided you need 1 unit of insulin for every 10 grams of carbohydrate, you would need 5 units of insulin to keep your post-meal blood sugar from rising above your target level.
Your insulin-to-carbohydrate ratio may change over time. In some people it will differ from one meal to another. You might take 1 unit of insulin for every 10 grams of carbohydrate for lunch but take 1 unit for every 15 grams at dinner. Keep the following in mind when counting carbohydrate grams:
By keeping track of what you eat and testing your blood sugar after meals and exercise, you can learn to estimate the effect of protein, fat, fiber, and exercise on the amount of insulin you need.
Count carbohydrate grams and eat a balanced diet by:
Other helpful suggestions
Test Your Knowledge
I can eat only a certain amount of carbohydrate at one sitting, or my blood sugar will be too high.
Calculate the carbohydrate content in the following breakfast. Use the information in the "carbohydrate foods" and "foods that contain protein" links to calculate the carbohydrate. The breakfast includes 2 eggs, 1 cup of milk, 1 slice of toast, and 2 teaspoons of margarine.
30 grams of carbohydrate
35 grams of carbohydrate
Now that you have read this information, you are ready to plan regular meals and snacks and calculate the amount of carbohydrate in your diet.
Talk with your diabetes specialist (doctor or other health professional, registered dietitian, or certified diabetes educator). If you have questions about this information, take it with you when you visit your diabetes specialist.
If you need help with carbohydrate counting or meal planning, see a registered dietitian.
If you would like more information on meal planning for people who have diabetes, the following resources are available:
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