Diabetes: Counting Carbs if You Use Insulin

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 Reference 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:

• Fruits and vegetables.
• Milk and yogurt.
• Starchy foods (such as breads, cereals, dry beans, and vegetables such as potatoes and corn).
• Sugary foods (such as candy and cakes).

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.

Carbohydrate counting helps prevent low or high blood sugar levels, which can cause medical emergencies. Over time, Reference high blood sugar levels can damage many body tissues and organs.

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 Reference insulin pump Opens New Window or take multiple insulin injections, you need to know how many grams of carbohydrate are in a meal to calculate how much Reference 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.

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 Reference 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:

• Portion control is important. If a package says it contains two servings and you eat the whole package, you need to double the number of grams of carbohydrate listed for one serving.
• Protein, fat, and fiber do not raise blood sugar very much. If you eat a lot of these nutrients in a meal, carbohydrate will convert to glucose more slowly than it would with a meal containing a small amount of protein, fat, and fiber.
• Exercise affects blood sugar, allowing you to use less insulin than you would if you were not exercising. Keep in mind that timing makes a difference. If you exercise within 1 hour of a meal, your body may need less insulin for that meal than it would if you exercised 3 hours after the meal.

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:

• Talking with a registered dietitian. He or she can help you plan the amount of carbohydrate to include in each meal and snack.
• Measuring your food portions. You won't always have to measure your food, but it may be helpful when you are first learning what makes up a standard portion.
• Reference Counting either grams or servings of carbohydrate. A registered dietitian will help you plan how much carbohydrate, including sweets, to have in each of your meals and snacks.
• Eating standard portions of Reference foods that contain protein. Foods that contain protein (meat and cheese) are an important part of a balanced diet.
• Limiting saturated fats. A balanced diet includes a limited amount of healthy fat. Talk with a registered dietitian about how much fat you need in your diet.

Other helpful suggestions

• Read Reference food labels Opens New Window Reference Opens New Window for carbohydrate content. Be careful to consider the serving size on the package.
• Check your blood sugar level. If you do this before and 1 hour after a meal, you will be able to see how the food you eat affects your blood sugar level.
• Record what you eat and your blood sugar results in a food record (What is a Reference PDF Opens New Window document?). At each regular visit with your registered dietitian or certified diabetes educator, or whenever you think your meal plan needs adjusting, you can review your food record.
• Get more help. The American Diabetes Association offers booklets to help people learn how to count carbohydrate grams in their diet, to measure and weigh food, and to read food labels. But you will still need to talk with a registered dietitian to establish a plan that fits your needs.

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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