Figuring Out Yor Insulin Dosage

Two methods to help determine insulin-to-carb ratios.

Theresa GarneroBy Theresa Garnero, APRN, BC-ADM, MSN, CDE

Warning: Please work with your healthcare provider. Although the following suggestions may be common approaches to insulin dosage adjustment, you want to be sure you are safe and under the guidance of a professional before changing your insulin regime. It takes time to understand these steps and to see how your body responds.

For those taking rapid-acting insulin before meals (Humalog, NovoLog, Apidra), you want to know how many carbohydrates 1 unit of insulin covers. (Do not attempt to figure this out until your basal insulin has been calculated to give you a pattern of fairly stable, in-range fasting glucose values, otherwise, you can miscalculate your insulin-to-carb ratio and need to make further mealtime or bolus adjustments.) In figuring out your insulin dosage, two common methods to determine insulin-to-carb ratios are the weight method and an individual plan. (1)

The Weight Method
The weight (in pounds) method assumes that as your weight increases, so does insulin resistance, and therefore, the more you weigh, and the more insulin you require. The weight method does not take into account the weight from muscle mass. People who are physically fit or those with type 1 diabetes, tend to be less insulin resistant, which is a down side of only using weight to calculate insulin sensitivity.


Weight Method

Based on your weight and the chart above, what is your insulin sensitivity factor? Write it down.  1 unit of rapid-acting insulin will cover ___________ grams of carbohydrate.

An Individual Plan
Are you curious to learn how your body reacts to 1 unit of insulin? Great. Prepare to gather two weeks worth of data of high-gear glucose monitoring. Check your glucose before one meal and three hours later. Try not to exercise, snack, or take extra insulin during those three hours to eliminate variables. Ideally, your glucose pre- and post meal should be within 30 points for this purpose. Start with two weeks worth of pre-breakfast and 3 to 4 hours after breakfast and note if the insulin-to-carb ratio made your glucose increase, stay the same, or drop.

For example, let's look at a week's worth of data:

Day 1
Meal Date (B, L, D): 2/1
Pre-breakfast glucose: 151
Grams of carb eaten: 50
Units of rapid acting insulin: 6
Insulin-to-carb ratio (carb divided by units of insulin): 1:8
(50 carbs divided by 6 units = 8.33 points of glucose affected by 1 unit of insulin)
3 to 4 hour post-breakfast glucose: 93
Comments: 1:8 ratio makes glucose drop

Day 2
Meal Date (B, L, D): 2/2
Pre-breakfast glucose: 123
Grams of carb eaten: 50
Units of rapid acting insulin: 5
Insulin-to-carb ratio (carb divided by units of insulin): 1:10
(50 carbs divided by 5 units = 10 points of glucose affected by 1 unit of insulin)
3 to 4 hour post-breakfast glucose: 86
Comments: 1:10 makes glucose drop a little

Page: 1 | 2

Last Modified Date: June 17, 2013

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