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Patient education: Carb counting for adults with diabetes (The Basics)

Patient education: Carb counting for adults with diabetes (The Basics)

What is carb counting? — Carb counting is a type of meal planning that many people with diabetes use. It is a way for people to figure out how many "carbs" they eat. "Carbs" is short for "carbohydrates."

Our body breaks down the food we eat into 3 main types of nutrients: carbohydrates, proteins, and fats. Carbohydrates are sugars and starches that come from food. The body uses carbohydrates for energy.

Why do I need to count carbs? — People with diabetes need to pay attention to how many carbs they eat. This is because carbs raise your blood sugar level.

Carb counting helps you:

Choose the right amount of insulin to take before meals and snacks – If you take insulin before meals, the dose to use depends on several things, including the amount of carbs you plan to eat. (It also depends on how much you plan to exercise and your blood sugar level.)

Plan your meals and snacks for the day – You can use carb counting to figure out how many carbs you should eat at each meal and snack. This will help you make sure you eat the right amount over the entire day.

Keep your blood sugar level under control – Spreading out the carbs you eat over a whole day can help keep your blood sugar from getting too high. If you take insulin or another diabetes medicine that can cause low blood sugar, eating about the same amount of carbs at each meal every day also helps keep blood sugar from getting too low. Reducing the amount of carbs you eat can help control your diabetes better and prevent medical problems that diabetes can cause.

Your doctor, nurse, or dietitian (food expert) can help you figure out how many carbs to try to eat each day. This will depend on your eating habits, weight, activity level, and which diabetes medicines you take.

People who take insulin before meals need to be very careful in counting the carbs in every meal and snack. This is so they can give themselves the right amount of insulin. If the insulin dose doesn't match the amount of carbs, their blood sugar might get too low. Other people might be able to be a little more flexible as long as they get about the same amount of carbs each day.

Which foods have carbs? — Foods with a lot of carbs include:

Grains – These include bread, pasta, rice, and cereal.

Fruits and starchy vegetables – Starchy vegetables include potatoes, corn, and squash.

Milk and other dairy products – Dairy products include cheese and yogurt.

Foods with added sugar – These include sweets and baked goods likes cookies and cakes, as well as sugary drinks like juice and soda.

It is best to get most of your carbs from fruits, vegetables, whole grains (like whole-wheat bread, whole-grain cereals, and brown rice), and low-fat milk and dairy products.

How do I count carbs? — To count carbs in packaged foods, you need to check the food's nutrition label (if it has a label).

On the label (figure 1), check for these things:

"Total Carbohydrate" number – This tells you how many carbs are in 1 serving size of the food. If you eat 1 serving, then the number of carbs you eat is the same as the number of total carbohydrates.

"Serving size" – This tells you how much food is in 1 serving. If you have 2 servings, the number of carbs will be 2 times the number of carbohydrates listed.

"Dietary Fiber" – Fiber is a carb that is not digested, which means it does not raise blood sugar. Foods with a lot of fiber can help control your blood sugar. If a food has more than 5 grams (g) of fiber, you need less insulin if you eat that food. So, if you are calculating an insulin dose, you should only count the carbs that are not from fiber (figure 1).

What is exchange planning? — Exchange planning, or the "exchange system," is a way for people to plan their meals without reading labels. This can be helpful since many foods don't come with a nutrition label.

The exchange system involves knowing how much of different foods have about 15 grams of carbs (table 1 and table 2 and table 3). Your doctor, nurse, or dietitian gives you a certain number of "carb choices" to eat with each meal and snack (table 4). Each "choice" is a portion of food that has about 15 grams of carbs. Knowing your options will make it easier to "exchange" 1 carb choice for another as you plan your meals and snacks. For example, 1 small apple could be exchanged for 1/3 cup of pasta.

How can I plan my meals? — First, make sure you know how many carbs you should be eating each day. As your doctor, nurse, or dietitian if you are not sure.

Here are some tips that might help:

Spread out your carbs over 4 to 6 small meals each day instead of 3 big ones

Eat a similar number of carbs at each meal, for example, at each dinner

Eat your meals at a similar time each day

Plan your meals ahead of time

Use the "plate method." This is a simpler way to make sure you get a good balance of carbs and other nutrients with each meal. It is not as exact as counting all your carbs, but can be helpful for people who struggle with this. If you take insulin before meals, it is better to adjust your insulin dose by counting how many carbs you plan to eat instead of using the plate method.

For the plate method, you start with a plate about 9 inches (23 cm) across. Then fill it with (figure 2):

1/2 non-starchy vegetables

1/4 protein

1/4 carbs

Follow your doctor's instructions for how and when to check your blood sugar. This can help you learn how certain foods affect your blood sugar.

Keep track of your meals and blood sugar levels. Show this to your doctor or nurse so they can adjust your treatment if needed. If you take insulin, you will also need to keep track of your exercise patterns and how much insulin you give yourself with each dose.

If you take insulin, make sure you understand how to use it. This includes knowing how to adjust the dose based on your blood sugar level and how many carbs you plan to eat.

Remember that other things besides carbs can raise or lower your blood sugar level. These things can include exercise, getting sick, drinking alcohol, travelling, and stress. If you take insulin, make sure you know how and when to adjust your dose in these situations.

If you are having trouble counting carbs or keeping your blood sugar under control, talk to your doctor or nurse. They can help. A dietitian can also help you plan specific menus that will give you the right amount of carbs each day.

For more information, you can also get a book on counting carbs or check the American Diabetes Association website (

More on this topic

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Patient education: Treatment for type 2 diabetes (The Basics)
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Patient education: Low blood sugar in people with diabetes (The Basics)

Patient education: Type 2 diabetes and diet (Beyond the Basics)
Patient education: Type 2 diabetes: Treatment (Beyond the Basics)

This topic retrieved from UpToDate on: Jan 01, 2023.
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