Diabetes and Carbohydrates: What You Need to Know

Understanding the relationship between carbohydrates and diabetes management can help you recognize the effects of dietary choices on your blood sugar levels.  “Carb counting” or tracking the type, amount, and timing of carbohydrate intake, can help you manage your metabolic control in the long run.¹ 

Carbohydrates, or carbs, may significantly impact diabetes management.² When you consume foods or drinks containing carbs, your body breaks them down into glucose, which raises the glucose level in your blood. This glucose serves as fuel to keep you energized.

After your body breaks down carbs into glucose, your pancreas releases insulin to help your cells absorb that glucose.²  If you’re living with diabetes, however, this process is disrupted. In type 1 diabetes, the pancreas does not produce any or enough insulin, whereas in type 2 diabetes, the pancreas does not produce enough insulin, combined with insulin resistance, resulting in a buildup of glucose in the bloodstream.

Hyperglycemia, or high blood glucose levels, can occur when there isn't enough insulin in your body to promote the transport of glucose in your cells or when your cells don't respond effectively to the insulin, leaving excess glucose in the blood. Hypoglycemia, or low blood glucose levels, can result from insufficient carbohydrate intake or an imbalance in medications.³

To effectively manage your diabetes, it is crucial to achieve a balance in the carbs you consume.¹ 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.⁴

Keep in mind that these carb and blood glucose level targets aren't the same for everyone. What works for one person may affect another person's blood sugar levels differently. Discuss your ideal blood sugar levels and diet with your healthcare provider.

Carbohydrates can be classified into three main types: sugars, starches, and fibers.⁵  They are made up of sugar molecules, which are classified as simple carbohydrates or complex carbohydrates. Carbohydrates are not only important as an energy source but can also have a beneficial effect on overall health.⁶

Simple carbohydrates 

Simple carbohydrates, also known as simple sugars, are composed of sugars that have a basic
chemical structure of one or two sugars.⁷ Single sugars (monosaccharides) include fructose and glucose, while double sugars (disaccharides) are sucrose, maltose, and lactose. 

Simple carbohydrates are often called fast-acting carbs as they quickly convert into energy due to their basic chemical structure, causing a rapid increase in blood glucose levels.^7,8 

Complex carbohydrates

Complex carbohydrates, like fiber and starches, are made up of three or more sugars.⁷ These are called polysaccharides and can be found in grains, fruits, vegetables, and legumes. Complex carbohydrates are often called “slow-acting carbs” since they take longer to break down and don’t immediately affect blood sugar levels.⁸

It isn’t enough to just say that carbohydrates are simple or complex; you should also think about how they affect blood sugar and chronic illnesses.⁶ The glycemic index and glycemic load were created to address the need for a more complete understanding of the impact of carbohydrate-rich foods.⁹

Keeping track of the total grams of carbohydrates consumed is critical for controlling blood sugar levels.¹

At first, carb counting can be a little challenging. Foods with multiple ingredients make it hard to calculate totals. And official serving sizes often have no relationship to the servings people consume.

It can be easy to get overwhelmed by how many “healthy” foods are high in carbs and how many “unhealthy” foods aren’t. Remember that making small changes and sticking to them can have huge benefits.¹⁰

While there are several ways to count carbs, it’s really about personal preference. The best carb counting method is one that addresses your personal medical and lifestyle needs. Talk to your healthcare team, or seek the support of a registered dietitian nutritionist or Certified Diabetes Care and Education Specialist to figure out what is best for you.

When it comes to actual carb counting, it’s important to include dairy products, fruits, and vegetables, along with grains and sweets. Approximately 15 grams of carbohydrates can be found in¹¹:

• Starches: 1 slice of bread, 1/3 cup of cooked pasta, 3/4 cup of dry cereal, or 4-6 crackers
• Fruit: 1 small piece of fruit or ½ cup of fruit juice
• Milk: 1 cup of nonfat (skim) milk, or 3/4 cup of yogurt
• Desserts: 2 small cookies or 1/2 cup of ice cream

Regardless of your meal plan's total carbohydrate content, it's key to focus on high-quality, nutrient-dense, fiber-rich, minimally processed carbohydrates.¹²

Carb counting tips

• Read the label: Sometimes, the carb count is easy to find. Take a moment to double-check the nutrition label. 
• Understand serving sizes: Measure breakfast cereal or weigh pasta before it goes into the pot to get a sense of recommended serving sizes. 
• Make a mental note: Once it’s clear how a 3/4 cup serving of cereal fits into a bowl, for example, it’ll be easier to make decisions without needing to use measuring tools.
• Try a hand: A fist can help guide what a cup of food looks like. A cupped hand is about half a cup, whereas the palm equals about 85 to 115 grams or 3 to 4 ounces.
• Use an app: Websites and apps can help by offering complete nutritional information. 
• Glycemic Index/Load: You can further enhance your carb counting by considering the glycemic index and load of foods.

The glycemic index (GI) is a way to categorize carbohydrate foods based on how quickly they are absorbed by the body and affect blood sugar levels.⁹ Foods ranked less than 55 are considered low glycemic index, foods ranked 56-75 are considered moderate, and foods ranked 76 and 100 are considered high.

• Low-glycemic index foods are absorbed more slowly and reduce both the glycemic response and the corresponding insulin release.
• High-glycemic index foods are quickly absorbed and raise blood sugar levels more rapidly.⁹

A food's glycemic index is affected by a variety of factors, including ⁹ its form, how it is combined in a meal, cooking time, acidity, protein/fat content, and soluble fiber. All of these factors together influence how food impacts blood sugar levels.

But glycemic index alone doesn’t cover the complete effect on your blood glucose levels. There are other factors to consider, such as how quickly glucose enters your bloodstream and how much glucose is in a serving of food, since GI doesn't take it into account.⁹ In this case, the glycemic load (GL) is useful for determining how a meal actually affects blood sugar levels. 

How to calculate glycemic load

Glycemic load is also measured on a scale, with values less than 10 considered low and those greater than 20 considered high.⁹ Multiply the glycemic index by the amount of carbs in a food and divide by 100 to get its glycemic load.

For example, one small apple has a glycemic index of 39 and 15 grams of carbohydrates, so to calculate its GL, you would multiply 39 by 15 and then divide by 100: 

Some foods with a low glycemic index may have other components that are not necessarily healthy.¹³ Foods with added sugar or foods that contain both saturated fat and carbohydrates (like certain sweets) can still have a low glycemic index.GI and GL doesn’t account for other overall nutritional information about the food. For example, whole milk has a low GI and GL value, but it's high in fats and calories.

The use of the glycemic index and glycemic load in planning meals for blood sugar control is up for debate, but it's seen as a helpful tool for those with type 2 diabetes and weight concerns. ⁹

Now that you understand how the type and amount of carbohydrates in food can affect your blood sugar levels, you can start learning more about how to read the food labels.

If you’re living with diabetes, counting carbs is an important part of managing blood glucose levels. This requires special attention to the carbohydrates section on nutrition labels. When it comes to carbs for people with diabetes, there’s no one rule for how many carbs to eat. 

Experts recommend that you speak to a doctor to develop an individualized meal plan with the right balance of carbs to other nutrients for your body’s needs.^1,14

It’s important to note that not all carbohydrates are equal. Here are a few different ways carb contents are addressed on nutrition labels.

Total carbohydrates

This line represents the total amount of carbs in one serving.¹⁵ This number is made up of both complex carbohydrates like fiber and starch, and simple carbohydrates like sugar.¹⁶

Dietary fiber

Some foods, like vegetables and many fruits, contain carbohydrates referred to as “dietary fiber.”¹ These complex carbohydrates slow the body’s absorption of sugar, which is very helpful for maintaining steady blood sugar levels.¹⁷ When it comes to fiber intake, aiming for about 35 grams per day is recommended, but this can vary by person, so keep an eye on your blood glucose and discuss any changes with your healthcare provider for personalized advice.

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 alcohols do not contribute to blood sugar as much as other forms of carbs can because they are not fully absorbed.¹⁸

Sugar

Sugar is the simplest kind of carbohydrate, which just means that it’s easiest for the body to absorb.⁵ As such, sugar has the most direct impact on blood sugar and is listed separately from total carbs to help anybody seeking to limit sugar, like people with diabetes, find foods that fit their diets.

Additional sugar

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.¹⁵

Choosing the right foods for you

With all of this in mind, choosing foods high in dietary fiber and low in sugar can help you maintain your ideal blood sugar range.¹ Everyone needs carbs, and it’s much easier to maintain a balanced diet when you choose the right carbs. Eat whole grains and foods high in dietary fiber, and consider the quality, quantity, and type of carbohydrates to help manage your blood sugar levels. Remember to monitor your blood glucose closely when you change your diet and discuss them with your healthcare provider for personalized advice.

Resources

1. The Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD), Aas AM, Axelsen M, et al. Evidence-based European recommendations for the dietary management of diabetes. Diabetologia. 2023;66(6):965-985. doi:10.1007/s00125-023-05894-8

2. Ojo OA, Ibrahim HS, Rotimi DE, Ogunlakin AD, Ojo AB. Diabetes mellitus: From molecular mechanism to pathophysiology and pharmacology. Med Nov Technol Devices. 2023;19:100247. doi:10.1016/j.medntd.2023.100247

3. Yanai H, Adachi H, Katsuyama H, Moriyama S, Hamasaki H, Sako A. Causative anti-diabetic drugs and the underlying clinical factors for hypoglycemia in patients with diabetes. World J Diabetes. 2015;6(1):30-36. doi:10.4239/wjd.v6.i1.30

4. Carbs and Diabetes | ADA. Accessed December 6, 2023. https://diabetes.org/food-nutrition/understanding-carbs

5. Campos V, Tappy L, Bally L, Sievenpiper JL, Lê KA. Importance of Carbohydrate Quality: What Does It Mean and How to Measure It? J Nutr. 2022;152(5):1200-1206. doi:10.1093/jn/nxac039

6. Ioniță-Mîndrican CB, Ziani K, Mititelu M, et al. Therapeutic Benefits and Dietary Restrictions of Fiber Intake: A State of the Art Review. Nutrients. 2022;14(13):2641. doi:10.3390/nu14132641

7. Chandel NS. Carbohydrate Metabolism. Cold Spring Harb Perspect Biol. 2021;13(1):a040568. doi:10.1101/cshperspect.a040568

8. Harvard T.H. Chan School of Public Health. Carbohydrates and Blood Sugar. The Nutrition Source. Accessed December 6, 2023. https://www.hsph.harvard.edu/nutritionsource/carbohydrates/carbohydrates-and-blood-sugar/

9. Kirpitch AR, Maryniuk MD. The 3 R’s of Glycemic Index: Recommendations, Research, and the Real World. Clin Diabetes. 2011;29(4):155-159. doi:10.2337/diaclin.29.4.155

10. Papakonstantinou E, Oikonomou C, Nychas G, Dimitriadis GD. Effects of Diet, Lifestyle, Chrononutrition and Alternative Dietary Interventions on Postprandial Glycemia and Insulin Resistance. Nutrients. 2022;14(4):823. doi:10.3390/nu14040823

11. Kulkarni KD. Carbohydrate Counting: A Practical Meal-Planning Option for People With Diabetes. Clin Diabetes. 2005;23(3):120-122. doi:10.2337/diaclin.23.3.120

12. ElSayed NA, Aleppo G, Aroda VR, et al. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes—2023. Diabetes Care. 2022;46(Supplement_1):S68-S96. doi:10.2337/dc23-S005

13. Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. 2019;393(10170):434-445. doi:10.1016/S0140-6736(18)31809-9

14. ElSayed NA, Aleppo G, Aroda VR, et al. 8. Obesity and Weight Management for the Prevention and Treatment of Type 2 Diabetes: Standards of Care in Diabetes—2023. Diabetes Care. 20233/12;46(Supplement_1):S128-S139. doi:10.2337/dc23-S008

15. Nutrition C for FS and A. How to Understand and Use the Nutrition Facts Label. FDA. Published online January 23, 2024. Accessed February 8, 2024. https://www.fda.gov/food/nutrition-facts-label/how-understand-and-use-nutrition-facts-label

16. Kristeen Cherney. Simple Carbohydrates vs. Complex Carbohydrates. Healthline. Published May 23, 2023. Accessed December 6, 2023. https://www.healthline.com/health/food-nutrition/simple-carbohydrates-complex-carbohydrates

17. Mayo Clinic Staff. Dietary fiber: Essential for a healthy diet - Mayo Clinic. Mayo Clinic. Published Nov 4, 20222. Accessed December 6, 2023. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

18. Msomi NZ, Erukainure OL, Islam MdS. Suitability of Sugar Alcohols as Antidiabetic Supplements: A Review. J Food Drug Anal. 2021;29(1):1-14. doi:10.38212/2224-6614.3107