Are You on Insulin and Not Carb Counting?

Using the insulin-to-carb ratio can help you reach your A1C goal.

Lara Rondinelli By Lara Rondinelli, RD, LDN, CDE

I see many patients with type 1 and type 2 diabetes on insulin who are having trouble reaching their Hemoglobin A1C goal. These patients are on long-acting (Lantus or Levemir) insulin and rapid-acting (Humalog, Novolog, Apidra) insulin and averaging 4 shots per day. They may present with an A1C above 8% and are frustrated with their inability to improve their blood glucose control, while experiencing both hypoglycemia and hyperglycemia. There could be many reasons for this, but I've seen a handful of patients lately that have something in common — they are dosing their rapid-acting insulin before meals based only on their blood sugar levels. They are not counting carbohydrates or using insulin-to-carb ratios. In other words, they are missing a big part of the equation that goes into insulin dosing with meals.

For example, a patient may have a scale that states he should take 6 units of rapid-acting insulin before meals when his BG level is between 150-200mg/dl. So, with a blood glucose of 180mg/dl, he would take 6 units before a lunch (meal A) that consists of a grilled chicken salad, medium size apple, and water. He would take the same 6 units if he ate a lunch (meal B) of a turkey sandwich on whole-wheat bread, cup of black bean soup, and an apple. Meal A contains about 30 grams carbohydrates and meal B contains 80 grams carbohydrates. However, the patient took 6 units of insulin before each meal based on the blood sugar of 180mg/dl. Post-prandial blood glucose levels vary greatly in these patients. They may have hypoglycemia with one meal and hyperglycemia with another. There is often no pattern to their blood glucose levels because so much varies depending on how many grams of carbohydrates they eat. In order to get better control, these people can benefit from carbohydrate counting and using insulin-to-carb ratios.

Step 1

The first step in getting better control is learning how to count carbohydrates. Making an appointment with a registered dietitian who is also a certified diabetes educator (CDE) is recommended. Accurate carbohydrate counting takes practice, measuring, record keeping, and good resources. Some people say that counting carbs takes too much time or is too hard. The time it takes to learn the carb count of various foods is time well spent and before long, carb counting will become second nature. Learn more about carb counting here.

Step 2

Step 2 involves dosing insulin before meals based on insulin-to-carb ratios. Your doctor or CDE can help you determine your insulin-to-carb ratio. Here's how it works. Before you eat, figure out how many grams of carbs you will be eating. Then, based on your insulin-to-carb ratio, calculate how much rapid-acting insulin to take for that amount of carbs. For example, if you have an insulin-to-carb ratio of 1:10 with meals, you take 1 unit of rapid-acting insulin for every 10 grams of carbs you eat. In the example above, meal A contained 30 grams of carbs. To use the insulin-to-carb ration of 1:10, divide 30 grams by 10 and take 3 units of rapid-acting insulin. For meal B, which contained 80 grams of carbs, you would take 8 units of rapid-acting insulin (80 divided by 10) if you had an insulin-to-carb ratio of 1:10. Your CDE or MD will also give you a correction or sensitivity factor to use if your blood glucose is too high. The correction or sensitivity factor is the drop in blood glucose level caused by each unit of insulin you take. It is measured in milligrams per deciliter (mg/dl). This would be in addition to the insulin-to-carb ratio because you need extra insulin for the high blood sugar (along with insulin for the carbs you eat). Keep in mind that you may need to adjust your insulin-to-carb ratio and that working with a CDE and keeping good food-glucose records can really help improve your blood glucose levels.

I'll leave you with a great recipe that delivers 10 grams of carbohydrates per serving: Chicken and Vegetables with Cashews. Enjoy!

Read Lara's bio here.

Read more of Lara Rondinelli's columns.

NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition. 

Last Modified Date: April 11, 2013

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by Brenda Bell
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