The Importance of Counting Carbs If You Have Diabetes

white bread thumbCounting carbohydrates (carbs) is a key strategy for meeting blood glucose levels. This is because the carbs in food are broken down into glucose. Insulin helps to regulate glucose levels, but people with diabetes do not make enough of it. This is why counting them is so important.

Knowing the number of carbs a person needs to eat each day is important to make carb-counting work. It will be based on several things, such as activity level and any medicines taken to control glucose levels. There are doctors and dietitians that can help a person learn how many carbs are needed at each meal and snack.

The Basics of Counting Carbs

Eating the right amount of the right kind of carbs can keep glucose levels in the healthy range. Carbs come in 3 forms:

Planning a Meal by Counting Carbs

Carbs are listed on a food's nutrition facts label. Look for “total carbohydrate” on the label. This number accounts for carbs from starches, sugars, and fiber.

It can be harder to count carbs when dining out or eating foods that do not have a label, like fruits and vegetables. A person will need to know the number of carbs needed at each meal and the average number of carbs in a serving from each food group. This can help a person plan meals. Use these averages to count the carbs in a meal:

Type Carbs (grams)
Starch 15
Fruit 15
Milk 12
Vegetable 5
Meat 0
Fat 0

Based on this table, 1 serving of oatmeal with milk has 27 grams of carbs:

15 (starch) + 12 (milk) = 27 grams of carbs

It's also good to know about serving sizes. Tools like a food scale, measuring cups, and measuring spoons can help a person keep portions on track. People can also use general serving sizes when they are not able to measure. For example, there are about 15 grams of carbs in:

  • 1 small piece of fruit (4 ounces)
  • ½ cup canned or frozen fruit
  • 1 slice of bread (1 ounce)
  • ½ cup cooked cereal
  • ¼ of a large baked potato
  • ½ cup ice cream
  • 2/3 cup plain fat-free yogurt
  • 1 cup milk
  • 2 small cookies

Carb-counting books and smartphone apps can also help a person plan meals.

Filling Up With Fiber

Fiber is not digested the same way as other carbs. A person can subtract half the amount of fiber from the total carbs in any food that has more than 5 grams of fiber in a serving. As a bonus, fiber-rich foods help with digestion and keep a person feeling full longer. A healthy diet should have at least 25 to 30 grams of fiber each day. Most of us get less than this, so any increase of dietary fiber is a plus. Choosing whole-grain products will help a person meet fiber goals (and get some of the vitamins and minerals that are lost in refined products).

All Carbs Are Not Created Equal

You can eat the right number of carbs but all the wrong foods. For example, a small piece of fresh fruit has the same number of carbs as ½ cup of the same canned fruit. But eating a fresh pear is far more nutritious because it does not have refined sugar. You also get extra fiber from the pear's skin. A person with diabetes needs to count carbs but must also remember to make overall healthy choices and work a variety of healthy foods into their diet.


American Diabetes Association

Joslin Diabetes Center


Canadian Diabetes Association

Public Health Agency of Canada


American Diabetes Association. Standards of medical care in diabetes - 2020. Diabetes Care. 2020 Jan; 43 (Suppl 1):S1-S212.

Dietary considerations for patients with type 2 diabetes. EBSCO DynaMed website. Available at: Accessed August 21, 2020.

Dietary guidelines for Americans 2015-2020. Office of Disease Prevention and Health Promotion website. Available at: Accessed August 21, 2020.

Increasing fiber intake. UCSF Health website. Available at: Accessed August 21, 2020.

What are net carbs? Diabetes Forecast—American Diabetes Association website. Available at: Accessed August 21, 2020.

Last reviewed March 2020 by EBSCO Medical Review BoardDianne Scheinberg Rishikof MS, RD, LDN  Last Updated: 2/26/2021