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Diabetes: Counting Carbs if You Use Insulin

Diabetes: Counting Carbs if You Use Insulin


Managing the amount of carbohydrate (carbs) you eat is an important part of planning healthy meals when you have diabetes. Carbs raise blood sugar more than any other nutrient. Carbs are found in grains, starchy vegetables, fruits, and milk and yogurt. Carbs are also found in sugar-sweetened foods and drinks.

The more carbs you eat at one time, the higher your blood sugar will rise. Counting carbs can help you keep your blood sugar within your target range.

If you use insulin, counting carbs helps you match the right amount of insulin to the number of grams of carbs in a meal.

How do you count carbohydrate grams in your diet?

Carbohydrate (carb) counting is an important skill to learn when you use insulin. It allows you to adjust the amount of insulin you use so you can eat what you want and still keep your blood sugar at your target level. Here are some tips for counting carbs.

  • Know your daily amount of carbs.

    Your daily amount depends on several things, including your weight and how active you are. A registered dietitian or certified diabetes educator will help you plan how much carbohydrate to include in each meal and snack. For example, most adults can have 45 to 60 grams at each meal, which is 3 to 4 carbohydrate servings.

  • Count your carbs.

    To count carbs, you need to know how many carbs are in each type of food you eat. Most packaged foods have labels that tell you how many carbs are in one serving. For foods that aren't packaged, you'll need to know standard portions of carbohydrate foods. Each serving size or standard portion has about 15 grams of carbs. Portion control is important.

    • Measure your food portions. You won't always have to measure your food. But it may help when you're first learning what makes up a standard portion.
    • Read food labels for carb amounts, and be aware of the serving size. If a package contains two servings and you eat the whole package, you need to double the number of grams of carbs listed for one serving.
  • Figure out your insulin dose.

    By using the number of grams of carbs in a meal, you can figure out how much insulin to take. This is based on your personal insulin-to-carbohydrate ratio. For example, your doctor may advise you to take 1 unit of rapid-acting insulin for every 10 to 15 grams of carbs you eat. Here's how to figure out how much insulin you need:

    • Say your meal has 50 grams of carbs, and your doctor told you to take 1 unit of rapid-acting insulin for every 10 grams of carbs you eat.
    • Divide 50 by 10, which equals 5. You would need 5 units of insulin to keep your post-meal blood sugar from rising above your target level.
  • Record what you eat and your blood sugar results.

    Keep track of what you eat, and test your blood sugar after meals and exercise. This can help you figure out what effect exercise and different types of food have on the amount of insulin you need.

    • Protein, fat, and fiber don't raise blood sugar very much. If you eat a lot of these nutrients in a meal, carbs will change to glucose more slowly than they would with a meal that has a small amount of protein, fat, and fiber.
    • Exercise affects blood sugar. It allows you to use less insulin than you would if you didn't exercise. 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.
  • Consider advanced carb counting.

    Advanced carb counting takes into account the amount of fiber or sugar alcohols (a type of sweetener used in foods labeled "sugar-free") in a food. For example, if a food has 5 or more grams of fiber per serving, you can subtract half the amount of fiber from the total number of carb grams. A food that has 30 grams of carbs and 8 grams of fiber would be counted as 26 grams of carbs (8 ÷ 2 = 4, and 30 - 4 + 26).

    If you use a rapid-acting insulin, you may want to consider sugar alcohols if there are more than 5 grams of them in the food. Divide the number of sugar alcohols in half. Then subtract that number from the total carb count.


Current as of: May 9, 2022

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
Rhonda O'Brien MS, RD, CDE - Certified Diabetes Educator
Colleen O'Connor PhD, RD - Registered Dietitian

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