Today’s POTD is brought to you by the fear and terror I feel every time I have to order insulin, so below I’m going to review the different types of insulin, when to use them, and importantly how to order them.
Types of Insulin
There are four main classes of insulin: rapid-acting, short-acting, intermediate-acting, and long-acting. These classes are aptly named based on their onset time. Here is a summary of each class:
I know what you’re thinking – wow, that is a lot of options… which one do I chose?! How much do I give?! Do I give it subcutaneously or intravenously?! Well, luckily, the Maimo pharmacists simplified things for us by only having three types of insulin (lispro, glargine, and regular) and very thorough order sets. If you know your indication, SCM guides you through the rest.
Insulin administration comes in two flavors: subcutaneous and intravenous. Subcutaneous is the only dosage route for long-acting insulin but rapid and short-acting insulin can be given subcutaneous or intravenous. IV insulin should only be used when you are treating hyperkalemia, DKA or HHS. Otherwise, you should give insulin subq.
Dosage of insulin depends on the patient’s weight, blood glucose level, and insulin tolerance. This can be a lot to remember, so your best bet is to follow the order sets that I’ll go through next.
Acute Hyperglycemia (without evidence of DKA or HHS) can be managed with subq lispro (as well as IV fluids and addressing the underlying cause). The amount of insulin you give depends on the patient’s current glucose level and their sensitivity or resistance to insulin. Be sure to ask what their home insulin regimen is before ordering. Then you can easily order through the “Insulin Subcutaneous Ordering” order set.
Search for and open the order set “Insulin Subcutaneous Ordering”
Select the patients feeding status – eating, tube feeding or NPO
Scroll down to the “correction scale insulins” section and decide between very low dose, low dose, moderate dose, or high dose based on your patient’s home insulin regimen
Very low dose = for patients who are insulin naïve
Low dose = for patients who require less than 40 units per day
Moderate dose = for patients who require 40-80 units per day
High dose = for patients who require more than 80 units per day
Check the “insulin lispro correction scale injectable” under the appropriate dosing regimen. If you want to give a one-time dose in the ED double click the order to change the frequency from “3x/day, before meals” to “once” and make the start time “STAT”
DKA or HHS is treated with an IV infusion of regular insulin. We start the drip at 0.1 units/kg/hour and continue until the gap is closed. You may precede the drip with a bolus of IV lispro at 0.1 units/kg, but there is no evidence that giving a bolus is beneficial, and it can potentially cause hypoglycemia. Once the gap is closed, you can transition your patient to subq insulin by calculating the total amount of insulin administered IV and then give 50% of that total as subq glargine insulin. (Of course, there are many other aspects of DKA/HHS management which could be a separate POTD; I’m just highlighting some key points here.)
Search for and open the order set “ED DKA/HHS Ordering”
Scroll down to “insulin” and check the “insulin 100 units in NS 100ml” infusion. You will need to double click the order to input a dose.
Of note, the dose is listed as units/hr and should be calculated as 0.1u/kg/hr. If your patient weighs 70kg, you would give 7 units per hour.
If you want to bridge to subq insulin, go back to the same “ED DKA/HHA Ordering” but scroll down to “basal/long acting insulin”
Select “insulin glargine (100 units/ml) basal." Double click the order to input a dose.
Remember the dose will be 50% of the total IV insulin given.
Hyperkalemia is treated with a rapid bolus of IV insulin intended to shift potassium into the cells. Be sure to give this insulin with dextrose to prevent hypoglycemia.
Search for the “ED Hyperkalemia Order Set”
Select “insulin lispro (100units/ml) injectable IV push”
This will default to a dose of 5 units. You can re-dose again if needed.
Sources:
Our lovely ED Pharmacy team
https://rushem.org/2021/05/16/basic-management-of-diabetesnot-just-for-internists/
https://rebelem.com/benefit-initial-insulin-bolus-diabetic-ketoacidosis/