If you have diabetes, you might be using – or considering – a meal-planning approach called carbohydrate (carb) counting. Carbohydrate is the major nutrient that has the most impact on blood sugar levels compared with the other major nutrients, protein and fat. While you don’t need to stop eating foods that contain carbohydrate, such as bread, pasta, fruit, and milk, you’re likely going to need to control the amount of carb that you eat in order to help keep your blood sugars within your target range.
What is advanced carb counting?
First, let’s define “basic carb counting.” This meal-planning approach can be used by anyone who has diabetes. It typically outlines the number of carb grams or carb servings to aim for at every meal and at snack time. Your dietitian or diabetes educator might even give you a range of carb grams or carb servings for meals and snacks. For example:
- 45 to 60 grams/3 to 4 carb servings for meals
- 15 to 30 grams/1 to 2 carb servings for snacks
Basic carb counting is a helpful way to establish some consistency with your carb intake; in addition, many people find that this approach also helps with weight control (as long as you aren’t going overboard with protein and fat servings!).
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Advanced carb counting, on the other hand, is a more flexible approach. It lets the person decide how much carb they want to consume at meals and snacks, rather than needing to eat a set amount of carb. Advanced carb counting is appropriate for people with diabetes who take mealtime insulin, also called bolus, or fast- or rapid-acting, insulin. Examples of mealtime insulin include:
- Insulin aspart (brand names Novolog, Fiasp)
- Insulin lispro (Humalog, Admelog, Lyumjev)
- Insulin glulisine (Apidra)
Regular insulin is also a mealtime insulin, but isn’t used as often as the faster-acting insulins listed above. Also, many people who use an insulin pump use advanced carb counting, but if you inject mealtime insulin using a pen or a vial and syringe, you can do this, too.
A dietitian or diabetes educator teaches you how to calculate or match the dose of mealtime insulin to the amount of carb you plan to eat. If you don’t take mealtime insulin, advanced carb counting will not work for you.
How advanced carb counting works: Using an insulin-to-carb ratio
In order to properly use advanced carb counting, you will use what is called an insulin-to-carb ratio (ICR). The Academy of Nutrition and Dietetics says that “an insulin-to-carb ratio helps you dose how much rapid-acting insulin you need to ‘cover’ the carbohydrate you will eat at a meal or snack.”
More specifically, the ICR tells you how many grams of carb are covered by 1 unit of mealtime insulin. For example, a ICR might be 1 unit of insulin for 15 grams of carbohydrate. This is often written as an ICR of 1:15. If your ICR is. 1:15 and you eat 60 grams of carb, you would need to take 4 units of mealtime insulin. But don’t assume that your ICR. Is 1:15. There is no one ICR that will work for everyone, and you might also have a different ICR for each of your meals.
Also, realize that using an ICR takes some practice — and some patience. It can take some time to find the ICR that works best for you. ICRs can also change over time, based on lifestyle, changes in weight, changes in diet, etc.
How advanced carb counting works: Using a correction factor
Advanced carb counting doesn’t stop at using an ICR. That’s because your ICR determines the amount of mealtime insulin to take for the carbohydrate you will be eating. What it doesn’t take into consideration is your pre-meal blood sugar.
If your blood sugar is higher than your pre-meal target (usually 70 to 130 mg/dl), you will likely need to “correct” for this. This is where a correction factor, or CF, comes in. The CF is another type of ratio used to calculate the amount of insulin you need to take to bring your blood sugar into target range. The CF is added to (or subtracted from, if your blood sugar is too low) your mealtime insulin dose. An example of a CF is 50, sometimes written as 1:50. This means that 1 unit of mealtime insulin will lower blood sugar by 50 points.
Like the ICR, there is no one CF that will work for everybody, and it can vary based on time of day. Your CF could be 1:10 or 1:60, for example. Again, your health care team will work with you to determine your own CF.
Determining insulin-to-carb ratios and correction factors
There are different ways to calculate ICRs and CFs. Your provider or diabetes educator might use formulas to determine your ICR and CF. Examples would be the “500 rule” for an ICR and the “1800 rule for the CF. Alternatively, your team may base your ratios on your body weight.
Realize that these methods are just starting points: they often need to be adjusted as you start using them, and it’s very common for ICRs and CFs to change. Also, if you are interested in trying advanced carb counting, be sure to work with your provider, dietitian, or diabetes educator to help you determine your own ratios.
Succeeding at advanced carb counting
Advanced carb counting holds a lot of appeal for people with diabetes who take mealtime insulin. It offers the flexibility and spontaneity that people without diabetes have when it comes to eating. Rather than having to make sure you stick with a set amount of carb at a meal, you choose what works for you. You could eat a piece of chicken and a salad one night for dinner, and the following night, eat a plate of pasta. But before you rush into this type of meal planning, consider the effort that you will need to put into this. Here’s what it takes to “succeed”:
- Keeping appointments with your diabetes team to get started and for follow-up visits.
- Checking blood sugars before and after meals to evaluate your ratios.
- Carefully counting grams of carbohydrate, using food labels, carb counting books, or a carb counting app or website. (Not counting carb grams accurately can lead to high or low blood sugars after meals).
- Weighing and measuring food portions, rather than “guesstimating” — at least for a while, and even periodically, going forward.
- Keeping track of your food (especially carb) intake to see how your ratios work for you.
- Being careful not to “overdo” the amount of insulin that you take. Insulin stacking is a common occurrence when carb counting. This happens when a dose of mealtime insulin is given while a previous dose is still working (stacking one dose on top of the other). Doing so can lead to hypoglycemia (low blood sugar), and sometimes, severe hypoglycemia. Insulin pump users can take advantage of a pump feature that takes into account “active” insulin when calculating a bolus dose.
- Realizing that good nutrition and reasonable portions are important for overall health and for weight control. Yes, you can dose your mealtime insulin accordingly and eat a big plate of pasta, garlic bread, and a bowl of ice cream for dessert. But calories count, and if you’re not careful, you may find that you gain weight using this method.
Is advanced carb counting for you? Talk with your provider, your diabetes educator, or your dietitian to help you decide!
Want to learn more about carb counting? Read “Counting Carbohydrates Like a Pro” and “Getting Started With Carb Counting.”
