Sliding Scale Insulin
What is Sliding Scale Insulin?
Sliding scale insulin is a technique that uses a sliding scale based on your blood glucose to determine how many units of insulin to give before each meal. It is not a very common technique among people who have had type 1 because it isn't very accurate and leads to an increased risk of hyper- and hypoglycemia.
However, it is still used for some patients who have recently been diagnosed since it is a simpler system to help them get used to giving insulin that isn't as complicated as doing full carbohydrate counts with insulin ratios.
How to Use a Sliding Scale
First, your doctor or another licensed healthcare professional will provide you with a scale to use that indicates how many units of insulin to give based on your blood glucose. Each sliding scale is different and they are often customized for each patient, so it is not okay to use just any scale that you may find on the internet or elsewhere. If your doctor wants you to use this technique, they will provide you with a scale to use.
The simplest scales will have two columns, one displaying blood glucose ranges and the other indicating how many units of insulin to give. The image to the right is an example of a sliding scale.
Using a sliding scale is relatively simple. The first step is to check your blood glucose using a meter or a CGM. Then looking through the blood glucose column on the table and find the range in which your current blood glucose falls.
For example, if your current blood glucose was 238, then you would use the 201 - 250 range. If your blood glucose was 65, then you'd use the ≤70 (less than 70) range. If your blood glucose was 323, then you'd use the ≥300 (greater than 300) range.
Once you have found the range in which your blood glucose falls, move across to the insulin column where it will tell you how many units of insulin to give. For example, if your blood glucose falls in the 71 - 100 range, then you give 4 units of insulin. If your blood glucose falls in the 251 - 300 range, then you give 12 units of insulin.
Your doctor will instruct you on how many times per day to use your sliding scale and administer insulin. Frequently, they will tell you to use it before each meal (breakfast, lunch, and dinner) and sometimes once before bed (or around 10pm).
If you would like to practice using a sliding scale, scroll to the bottom of this page to view some practice problems with answers and explanations.
More Complicated Sliding Scales
One of the key advantages of using sliding scale insulin is that it is pretty simple to use, but because your activity levels and food intake change throughout the day, your doctor may provide you with a sliding scale that separates the insulin doses by meal or time of day like the one below.
When using a sliding scale like this, you still find the column with your blood glucose range, but now you use a different column of insulin units for each meal or time of day. This helps give you a little more control over your dosage that using just one scale every time.
Pros and Cons of Sliding Scale Insulin
Sliding scale insulin is not very commonly used anymore, and people who have had type 1 diabetes for a long period of time will almost ever use it. In fact, some studies have called it an "antiquated" tool that is "stuck in the past". That being said, here are the pros and cons to using sliding scale insulin.
Pros
Easy to use and understand, especially for newly diagnosed patients.
Is easier to use in long-term care facilities where not all staff may be trained or have time to calculate detailed carb counts
Cons
Does not take into account the effects of food on blood glucose.
Places patients at higher risk of hyper- and hypoglycemia (high and low blood glucose)
Increases the risk of future complications due to out of range blood glucose.
Conclusions
Sliding scale insulin is a tool that has some limited advantages in rare cases, but it is not something that should be used for long periods of time or by someone who has the ability to use more accurate dose calculation methods (such as carb counting). It is not something that you should try unless your doctors or healthcare provider has instructed you to do so and has taught you how to use it safely.
Practice Problems — Set 1
Use the sliding scale on the right to calculate how many units of insulin to give based on the blood glucose provided. The answers are provided in a drop down below.
Your current glucose is 103. How many units of insulin should be given?
Your current glucose is 443. How many units of insulin should be given?
Your current glucose is 68. How many units of insulin should be given?
Your current glucose is 250. How many units of insulin should be given?
Click to show answers
You should give 6 units.
You should give 14 units.
You should give 3 units.
You should give 10 units.
Practice Problems — Set 2
Use the sliding scale below to calculate how many units of insulin to give based on the blood glucose and meal/time of day provided. The answers are provided in a drop down below.
Your current glucose is 294 and you are about to eat dinner. How many units of insulin should be given?
Your current glucose is 60 and you are about to eat breakfast. How many units of insulin should be given?
Your current glucose is 187 and it is 10:00 p.m. How many units of insulin should be given?
Your current glucose is 147 and you are about to eat lunch. How many units of insulin should be given?
Click to show answers
You should give 10 units.
You should give 3 units.
You should give 0 units.
You should give 4 units.
Sources and Further Reading
American Diabetes Association. “Standards of medical care in diabetes--2013.” Diabetes care vol. 36 Suppl 1,Suppl 1 (2013): S11-66. doi:10.2337/dc13-S011
“Dosing Insulin.” Joslin Diabetes Center, https://www.joslin.org/patient-care/diabetes-education/diabetes-learning-center/dosing-insulin.
Sliding Scale Insulin Therapy: How It Works, Doses, Alternatives. 5 Apr. 2019, https://www.medicalnewstoday.com/articles/317171.