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How to Count Carbs

Carbohydrate counting is a good system to use when you need to balance food and medication such as insulin. If you use pills or long-lasting insulin only, you should not use this method.

To do carb counting, you need to know how many carbs are in different kinds of food. Knowing how to read nutrition labels is essential. Having access to a database of nutrition facts or a book that list them is key. Non-processed foods such as fruits, vegetables and meat are not required to use labels, so being able to find the information using other sources is very important.

One carb choice, or serving, is the amount of food that contains 15 grams of carbohydrate. Whether you eat 15 grams of carb from a piece of bread or 15 grams of carb from a cookie, the effect on your blood glucose level is about the same.

How do you know how much carb you should aim for at your meals? A dietitian is the best person to help answer this. A dietitian takes into account your medication, food likes and dislikes, eating schedule, weight goals and overall diabetes control to come up with a carb amount that's best for you. Work with your dietitan to find your insulin-to-carb ratio. This number is unique per person, and you may even need different ratios for different meals.

This ratio describes how much insulin you need to take to "cover" the carbohydrates in your meal. Let's say you have an insulin-to-carb ratio of 1:15. This means that you need to take 1 unit of your fast-acting insulin to cover every 15 grams of carb you eat. So, if you plan to eat 45 grams of carb at your meal, you will need 3 units of insulin.

Although you can find your sensitivity of carbohydrates and insulin by yourself, working with a dietitian is a must. They are trained not only to find your ratios but also to determine within your tolerance what are the correct numbers for you. Before starting your carb counting, consult a dietitian.

When using carb-counting, keep food records and check your blood glucose levels after meals for a while to make sure your ratio is correct.

If your blood glucose level is too high before a meal, you will need to take extra insulin, along with the insulin to cover your carbs. This extra insulin is called a correctional dose and also needs to be calculated with the help of your health-care team.

Carb counting really gives you the flexibility of eating as much or as little carb as you want while still maintaining good diabetes control, but don't forget that you still must eat a variety of foods and not load up on empty calories found in desserts and snack foods.

Source: American Diabetes Association and Carb Counting from Amy Campbell
Adapted by Editorial Staff, March 2007
Last update, August 2008