Diabetes and carbohydrates

Learn about carb counting and how it can help you control your diabetes.

Karen Flanagan, MA, RD, CDE | 20 February 2020
Carb counting not just insulin Hero

Has your doctor talked to you about watching the carbohydrates in the foods you eat? For a long time, people thought that counting carbohydrates wasn't necessary for those with type 2 diabetes, but that thinking is changing.

If you have a target number of carbs to eat at each meal or snack, accurately estimating carbohydrates can help you keep your numbers within your target range.1 It may help you avoid gaining weight and, by keeping your blood glucose in range, help you feel your best.2,3 Keep in mind that these carb and blood glucose targets aren't the same for everyone—what works for you may make another person's blood sugars fluctuate all over the map.

At first, counting carbs can be a little challenging. Foods with multiple ingredients can be difficult to guesstimate, and official serving sizes often have no relationship to the servings we actually see. We can be surprised how many "healthy" foods are high in carbs and how many "unhealthy" foods aren't.1 And, as many parents have learned, a "cup of milk" to a preteen boy may be whatever fits in an actual cup—somewhere between 8 and 24 ounces.

Carbohydrate counting isn't just for grains and sweets but also dairy products, fruits and vegetables. Approximately 15 grams of carbohydrate can be found in:

A single...

  • Slice of bread
  • Small pita
  • Small yogurt (3.5 oz)
  • Small banana
  • Small apple
  • Small glass of apple juice (4 oz)

1/2 cup of...

  • Cooked pasta or couscous
  • Lentils or dried beans

1 cup of...

  • Milk (8 oz)

1/3 cup of...

  • Cooked rice

3 teaspoons of...

  • Sugar
  • Honey

4 or 5...

  • Pieces of hard candy


  • Grapes

Carb counting tips

  • Read the label. Sometimes the carb count is right there in front of you. Take a sec to check.
  • Get out the cups. Measure your breakfast cereal. Weigh your pasta before it goes in the pot. Get a good sense of what a serving really looks like. Don't go more than a month or so without refreshing your memory, so those portions don't have a chance to grow.
  • Make a mental note. Once you've seen how a 3/4 cup serving of Bran-Os fits in your cereal bowl, you'll be in a better position to wing it.
  • Try your hand. Most people's palms are about the size of a 3- or 4-ounce portion. Your thumb is probably about a tablespoon. And your cupped hand can hold about a half cup.3
  • Use a calculator. You can find complete nutritional data from Web sites or apps such as MyFitnessPal® or Calorie Counter PRO.

How do you read a carbohydrate label?

For people living with diabetes, counting carbohydrates is an important part of managing blood sugar levels. That requires a special eye for the carbohydrates section of nutrition labels. There is no one rule for how many carbs people with diabetes should eat. Experts recommend speaking to your doctor to develop an individualized meal plan with the right balance of carbs to other nutrients for your body’s needs.4

Of course, not all carbohydrates are made the same. You may notice on a nutrition label that there are several lines addressing a food’s carb contents:

  • Total Carbohydrates: This line represents the total amount of carbs in one serving. This number is made up of both complex carbs like fiber and starch, and simple carbs like sugar.5
  • Dietary Fiber: Some foods, like vegetables and many fruits, contain carbohydrates referred to as “dietary fiber.”6 These complex carbs slow your body’s absorption of sugar, which is very helpful for maintaining steady blood sugar levels.7 In fact, if a serving of food contains at least 5 grams of dietary fiber, you can subtract half the total dietary fiber gram count from the total carb amount when counting carbs.8
  • Sugar Alcohol: While sugar alcohols do add to the total carb and calorie count for a food serving, they are often included in “sugar free” foods. Just like dietary fiber, sugar alcohol does not contribute to blood sugar as much as other forms of carbs can because they are not fully absorbed and you can subtract half the grams of sugar alcohol from the total carb amount for carb counting purposes.9
  • Sugar: Sugar is the simplest kind of carbohydrate, meaning it is the easiest for the body to absorb. As such, sugar has the most direct impact on blood sugar. It is listed out separately from total carbs to help anybody seeking to limit sugar, like people with diabetes, find foods that fit their diets.
  • Additional Sugar: Finally, some newer food labels may have an additional line under Sugar that lists anything that was added beyond the natural sugars contained in the other ingredients in the food.10

Remember: you can more effectively keep your blood sugar in the ideal range if you focus on eating foods high in dietary fiber and low in sugar. We all need carbs, even if you have diabetes, but choosing the right kinds of carbs goes a long way towards a balanced diet.

How are carbohydrates and sugar related?


Do you know any sugar thieves? Those well-meaning people who steal your real sugar and replace it with stevia, saccharin or other substitutes?

I think about one Thanksgiving a few years ago. There was a huge table filled with pies, cakes, candy and cookies—straight out of Willy Wonka's dream. The smell alone made my mouth water.

Next to that table was a smaller one with sugar-free apple pie, cookies and gummy bears, just for me. While it was extremely thoughtful and considerate of my diabetes, well, YUCK! I choked down a dry cookie and watched the others enjoy their desserts. Out of politeness, I ate some gummy bears, hoping the sugar alcohol-induced diarrhea wouldn't hit till after I got home. 

It's been over a decade since the experts announced that sugar is not our enemy. So why won't people believe it?

Most people don't understand that there are carbohydrates in sugar-free foods, too. It doesn't matter where the carbohydrate comes from. If you're on an insulin pump, you adjust your insulin to the amount of carbohydrate you eat. Instead of adapting our lives to food, we can adapt insulin to fit the situation.

For example a regular chocolate chip cookie has approximately 26 grams of carbohydrate in it. A similar sugar-free cookie has about 20 grams. Real apple pie has about 40 grams of carbohydrate per serving, and the sugar-free variety has about 37. A slice of yellow cake with frosting has about 40 grams of carbohydrate while the sugar-free version still delivers about 28 grams. The sugar-free ones are not free foods.

Why? Carbohydrates come from many sources, not just sugar. Sugar alcohols (usually ending in -tol, such as malitol, xylitol and sorbitol) have fewer calories than sugar, but often aren't as sweet. It takes more to get the same sweetness, making the carb count rival table sugar. And many carb-free sugar substitutes can't be used in cooking. Higher-carb options are used instead.

Whatever you choose to eat, remember that it's not the amount of sugar or where carbs come from that affect the overall rise in blood sugar. It's simply is the amount of carbohydrate. (Although the source of the carb may impact how quickly blood sugar rises.)

Show your friends that one healthy, sugar-free baked potato has approximately 29 grams of carbohydrate, while a sandwich cookie provides about 8 grams. Amazing!

And remember that even if the source of carbohydrate doesn't matter to your blood sugar, it will to the rest of your body. Carbohydrates, like everything you eat, should come from a variety of foods. One cannot live on cookies alone. Carbohydrates from whole grains, beans, fruits and dairy offer more essential nutrients, vitamins and minerals. Everyone, diabetes or not, should follow that rule.

Carbohydrate counting is a great tool to help control your diabetes. Combined with pumping, it can make your life and meals much more flexible and enjoyable. We need to educate the sugar thieves. Next year, I will be bringing desserts to Thanksgiving dinner. I already have a few new recipes in mind—and nothing will be sugar-free!

Karen Flanagan is a registered dietitian and certified diabetes educator who previously worked with pump users through Roche Diabetes Care. She has been wearing an insulin pump since 1992.

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MyFitnessPal is a registered trademark of Under Armour, Inc.

International Diabetes Federation. Diabetes education modules 2011: nutrition part 2: recommendations. Available at: https://www.idf.org/education/resources/modules-2011/download. Accessed September 15, 2015.

Queensland Health. Understanding the carbohydrate portion. Available at: https://www.health.qld.gov.au/__data/assets/pdf_file/0024/151737/diab_ch.... Accessed September 15, 2015.


1Hall M. Understanding advanced carbohydrate counting—a useful tool for some patients to improve blood glucose control. Today's Dietitian. 15(12):40, 2013. Available at: http://www.todaysdietitian.com/newarchives/120913p40.shtml. Accessed April 27, 2016.

2Watts SA, Anselmo JM, Kern E. Validating the AdultCarbQuiz: a test of carbohydrate- counting knowledge for adults with diabetes. Diabetes Spectrum. 24(3):154–160, 2011. Available at: http://spectrum.diabetesjournals.org/content/24/3/154.full.pdf. Accessed April 27, 2016.

3Polonsky WH. Diabetes Burnout: What to Do When You Can't Take It Anymore. Alexandria, VA: American Diabetes Association; 1999.

4“4. Lifestyle Management: Standards of Medical Care in Diabetes-2018.” American Diabetes Association, American Diabetes Association, Jan. 2018, care.diabetesjournals.org/content/41/Supplement_1/S38. Accessed October 23, 2018

5“Simple Carbohydrates vs. Complex Carbohydrates.” Healthline, www.healthline.com/health/food-nutrition/simple-carbohydrates-complex-ca.... Accessed October 23, 2018

6“22 High-Fiber Foods You Should Eat.” Healthline, www.healthline.com/nutrition/22-high-fiber-foods. Accessed October 23, 2018

7“Dietary Fiber: Essential for a Healthy Diet.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 22 Sept. 2015, www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-dep.... Accessed October 23, 2018

8Harding, Anne. “How to Count Carbs in 10 Common Foods.” Health.com, www.health.com/type-2-diabetes/how-to-count-carbs-in-10-common-foods#how.... Accessed October 23, 2018

9Harding, Anne. “How to Count Carbs in 10 Common Foods.” Health.com, www.health.com/type-2-diabetes/how-to-count-carbs-in-10-common-foods#how.... Accessed October 23, 2018

10Frey, Malia, and Richard N. Fogoros. “How to Read Nutrition Labels.” Verywell Fit, www.verywellfit.com/read-nutrition-labels-for-weight-loss-4065403. Accessed October 23, 2018