Pharmacology, part 31: Endocrine Medications - Insulin
April 01, 2021 Updated: December 29, 2021 10 min read 1 Comment
In this article, we cover one of the most commonly prescribed medications, and one you will encounter countless times in your nursing career—insulin. We'll give you an overview of rapid-acting, short-acting, intermediate-acting, and long-acting insulin, as well as some key administration tips to be aware of, side effects, nursing care, and patient teaching.
The Nursing Pharmacology video series follows along with our Pharmacology Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
When you see this Cool Chicken, that indicates one of Cathy's silly mnemonics to help you remember. The Cool Chicken hints in these articles are just a taste of what's available across our Level Up RN Flashcards for nursing students!
Diabetes Mellitus is one of the most common diseases in America. Diabetes causes chronic hyperglycemia (increased blood sugar levels) due to EITHER:
- Insufficient insulin production by the pancreas (Type 1), OR
- Insulin resistance of the cells in the body (Type 2)
Check out our article on Diabetes Mellitus for more detailed information. Need to remember the key facts of diabetes for the ATI, HESI, or NCLEX? Check out our Med-Surg flashcards for nursing students.
What is insulin?
Insulin is a hormone, usually naturally produced in our bodies, that helps decrease blood glucose levels. Insulin allows glucose to move from the bloodstream into the body's cells, where it can be used for energy. Check out our Med-Surg Endocrine System overview to learn more about insulin.
The manufactured forms of insulin, which we will cover here today, help diabetic patients control blood sugar. For each type of insulin, we will discuss their associated onset, peak, and durations—measures of time that indicate when the insulin is active in the body.
The onset of insulin is how long it takes for the insulin to first begin to act in the body and start lowering the blood sugar.
The peak of insulin is the time at which the insulin is exerting it's maximum action on the body.
The duration of insulin is the total amount of time it remains in effect in the body.
The four types of insulin
There are four types of insulin medications you will need to know for your Pharmacology exams and in your nursing practice. These include rapid-acting insulins like insulin lispro and insulin aspart, short-acting (regular) insulin, intermediate-acting insulin (NPH), and long-acting insulins like insulin glargine and insulin detemir.
Patients may be prescribed different types of insulin based on several factors, including age, activity level, diet, blood sugar management, and how long it takes their particular body to absorb and use insulin.
Rapid-acting insulins - Insulin lispro (Humalog), insulin aspart (Novolog)
Rapid-acting insulins like insulin lispro and insulin aspart work quickly over a narrow and predictable window of time. It is usually administered before or after meals.
The onset of rapid-acting insulin is 15 minutes. So rapid-acting insulin begins working in the body 15 minutes after it's taken.
The peak time of rapid-acting insulin happens around one hour after administration. So, one hour after administration, rapid-acting insulin is at its most effective in the body.
The duration of rapid-acting insulin is between 2 and 4 hours. So rapid-acting insulin is active in the body for about 2-4 hours after it's first taken.
If you have a patient requiring rapid-acting insulin, make sure their meal tray is readily available to help prevent hypoglycemia. If a patient were to take rapid-acting insulin and then not ingest a meal, the insulin would decrease the blood glucose already in the body rather than the new glucose from the food, resulting in hypoglycemia.
Short-acting insulins - Regular insulin (Humulin R, Novolin R)
Short-acting or regular insulin, takes longer to begin working than rapid-acting insulin, but still works fairly quickly and is usually taken before meals.
The onset of short-acting insulin is about 30 minutes, which means that it begins to work about 30 minutes after it's taken.
The peak time of short-acting insulin occurs between 2 and 3 hours. So, short-acting insulin is at its most effective 2-3 hours after administration.
The duration of short-acting insulin is between 3-6 hours, which means it will last in the body for 3-6 hours.
If you have a patient requiring short-acting insulin, make sure their meal tray is at least nearby. Unlike rapid-acting insulin, it does not need to be immediately available, but you should ensure it's delivered fairly soon. If a patient were to take short-acting insulin and not ingest a meal after the insulin's onset, blood glucose would likely drop too low. This access to a meal will help prevent hypoglycemia.
Intermediate-acting insulin - NPH (Humulin N, Novolin N)
Intermediate-acting insulin is often used to help control blood sugar between meals. Neutral Protamine Hagedorn (NPH) insulin is the most common intermediate-acting insulin that you will encounter.
NPH insulin has an onset time of 2 to 4 hours, which means it takes 2-4 hours to start working after it's administered.
NPH insulin has a peak time between 4 and 12 hours. So, 4 to 12 hours after it's administered, NPH insulin is at its maximum effectiveness in the body.
NPH insulin has a duration between 12 and 18 hours, which means it is active about that long in the body.
Neil Patrick Harris (NPH) is a hard-working actor of intermediate height. If you call him, he will be "on set" in 2-4 hours and he will stay there for 12-18 hours.
Long-acting insulins - Insulin glargine (Lantus), insulin detemir (Levemir)
Long-acting insulins like insulin glargine and insulin detemir are often used in the morning or at bedtime to help control blood sugar throughout the day.
Long-acting insulins like insulin glargine and insulin detemir have an onset between 3 and 4 hours.
Long-acting insulins do not have a peak. This is by design, because they are meant to control blood sugar for the entire day.
Long-acting insulins last for about 24 hours.
You will likely administer insulin many times in your nursing career, so it is important to remember these insulin administration tips and best practices.
When you administer insulin, it's important to rotate injection sites to help prevent lipohypertrophy.
Lipohypertrophy is scar tissue, or a thickened area of fat tissue that can form if insulin is injected in the same spot repeatedly.
The key adverse effect of insulin administration, and one of the common complications in patients with diabetes, is hypoglycemia. Hypoglycemia is a condition in which the blood sugar level is too low, which can occur as a result of insulin injection. If the insulin works too aggressively at decreasing the blood sugar levels and they drop too low, this can result in signs and symptoms like tachycardia, diaphoresis (sweating), shakiness, headache, and weakness.
Make sure to monitor your patient for these signs and symptoms.
Patients should be given guidance on the signs and symptoms of hypoglycemia so that they can recognize if it occurs and know how to respond.
Another important teaching tip for a patient taking insulin is that they may actually need additional doses of insulin during times of illness or stress. This is because the body may release hormones that increase blood sugar levels during illness.
Nursing care for Hypoglycemia
If your patient does experience hypoglycemia and they are fully conscious, then you can provide them with something that contains 15g glucose, like a 4oz glass of orange juice or an 8oz glass of milk.
If your patient is not fully conscious, then it is not safe to give them anything by mouth. You will need to administer glucagon, which is an injectable form of insulin.
Mixing insulins for patients is a skill you will likely need to use in your nursing career. For example, a patient may require a mixture of short-acting insulin with an intermediate insulin like NPH—and they can be mixed to avoid giving two injections when one will do. In the case of mixing insulins, you will need to remember that the clear insulin comes before the cloudy insulin. Clear before cloudy!
Steps for mixing insulins
- Inject air into the cloudy insulin. Remove your needle
- Inject air into the clear, shorter-acting insulin. Don't remove your needle.
- Draw up your short-acting insulin into the needle. Remove your needle.
- Draw up your longer-acting insulin.
Another one of Cathy's handy ways to remember the order of mixing insulins is to think of RN. Draw up Regular, then NPH.
A suspension is a liquid with small pieces of drug. The drug, in this case insulin, is not completely dissolved in the solution. An important tip to remember is to rotate the insulin suspension vial before administration. This helps to resuspend (redistribute) the insulin in the liquid and make sure it's evenly distributed for the right amount of medication to be administered.
Remember that short-acting insulins are supposed to be clear. If a short-acting insulin looks cloudy or discolored, dispose of it.
In this video, we are going to start our coverage of endocrine system medications. If you are following along with cards, I'm on card 99, which covers insulin, and there's a lot to talk about when it comes to insulin, so this video will be dedicated to just insulin.
Insulin can be used by both type 1 and type 2 diabetic patients. When we get into oral antidiabetic medications, those are just for type 2 diabetic patients.
There are four types of insulin to be familiar with. We have rapid-acting, short-acting, intermediate-acting as well as long-acting.
Alright, so let's start with our rapid-acting insulins which include insulin lispro, or Humalog as well as insulin aspart, or Novolog.
These medications have a very rapid onset. So onset is going to be 15 minutes, peak is going to happen around an hour, and duration occurs around 2 to 4 hours.
In terms of how I remember that these insulins that end in -log are rapid-acting is I think of a log rolling rapidly down a hill.
If you're going to give a patient a rapid-acting insulin, you want to make sure their meal tray is right in front of them to prevent hypoglycemia.
Alright. Let's talk about short-acting insulins which include regular insulin, which is Humulin R or Novolin R.
These medications have a slighter longer onset of action, so onset is about 30 minutes. Peak occurs around 2 to 3 hours, and duration occurs between 3 and 6 hours.
If you're going to give a patient some regular insulin, you want to make sure those meal trays are at least on the floor. It doesn't necessarily need to be in front of the patient, but you need to make sure that meal's going to be delivered fairly soon - okay? - so we don't end up with hypoglycemia.
Then we have our intermediate-acting insulin, which is NPH.
So NPH has an onset of 2 to 4 hours. It has a peak between 4 and 12 hours and a duration between 12 and 18 hours.
So the way I remember NPH is that Neil Patrick Harris, who's a famous actor, his initials are NPH, and let's say that Neil Patrick Harris, he is of intermediate height, and he's a very hard-working actor, so if you call him, he will be on set between 2 to 4 hours. He comes very quickly, and he stays a pretty long time, too. He will stay up to 18 hours because he's so hard-working.
Okay. And then, lastly, we have our long-acting insulins, which include insulin glargine, which is Lantus, or insulin detemir, which is Levemir. These medications have an onset between 3 and 4 hours. There is no peak with these medications, and the duration is about 24 hours.
So the way I remember that insulin glargine is long-acting, I think of a comfy pair of jeans, and they're so comfy that I want to wear them for 24 hours.
Okay. Let's talk about some important key points when it comes to insulin administration. When you're administering insulin, you want to make sure that you rotate sites to help prevent lipohypertrophy, which is the scar tissue you get if you inject that insulin in the same spot over and over again.
Also, the key adverse effect is hypoglycemia. So if we bring down our sugar levels too low, we can end up with signs and symptoms such as tachycardia, diaphoresis, shakiness, headache, and weakness. So we are definitely going to want to monitor our patient for those signs and symptoms and also make them aware of those signs and symptoms as well when the discharge from the hospital.
Other teaching, your patient may need extra doses of insulin during times of illness or stress. They definitely should not skip their insulin when they're sick, they actually might need a higher dose in order to adequately control their blood sugar levels.
If your patient does experience hypoglycemia and they are fully conscious, then you can provide them with some orange juice or milk, basically something that contains about 15 grams of glucose. So this could be like four ounces of juice or about eight ounces of milk.
If your patient is not fully conscious, then it is not safe to give them orange juice to drink. You will need to administer glucagon, which we will be covering in a future video here.
Then, if you are trying to mix insulins - if you are mixing a short-acting insulin with, say, an intermediate insulin, such as NPH - you always want to draw up clear before cloudy.
So how this works is, is you're going to inject air into the cloudy insulin, okay? Remove your needle. Inject air into the clear, shorter-acting insulin. Don't remove your needle. Draw up your short-acting insulin, which is your clear insulin, and then come back over here and draw up your cloudy insulin. So those are the steps. We're drawing up the clear before the cloudy.
Another tip for remembering what you draw up first is to think of registered nurse, or RN. You're drawing up regular before drawing up NPH.
So for insulin suspensions, you want to make sure you gently rotate the vial before administration.
And if a short-acting insulin looks cloudy or discolored, you're going to want to dispose of it.
So that is it for insulin. I know it's a lot of information. We will get into oral antidiabetic medications in my next video. Thanks so much for watching!
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