Insulin: Nursing pharmacology

Insulin is a medication used to treat clients with diabetes mellitus. Now, there are two main types of diabetes mellitus.

Type 1 diabetes mellitus arises when the pancreas is unable to produce insulin in order to maintain normal blood glucose levels.

On the other hand, type 2 diabetes mellitus is characterized by insulin resistance, which is when tissue cells have trouble responding to insulin in order to use glucose from the blood; as a result, tissue cells starve for energy despite having high blood glucose levels, which is called hyperglycemia.

Insulin is also used in the management of gestational diabetes, diabetic complications, like diabetic ketoacidosis and hyperglycemic hyperosmolar nonketotic coma, as well as in hyperkalemia.

Now, there are five main categories of insulin based on their onset of action and duration of effect. These include rapid-acting, short-acting or regular, intermediate-acting, long-acting, and ultra long-acting insulins.

All categories of insulin can be given subcutaneous injection or through an insulin pump, while the short-acting insulin can also be given intravenously.

Now the short-acting, or regular, insulin starts working 30 minutes after administration, with a peak effect at 2 to 3 hours, and can last between 6 to 8 hours.

Next, there’s rapid acting insulins which include insulin aspart, lispro, and glulisine. These medications begin working within 5 to 15 minutes of administration, with a peak effect at 30 minutes, and may last for 3 to 5 hours.

Another rapid acting insulin is inhaled insulin, which can only be used as an adjunct to therapy with injected insulins, and never by itself.

Next up is the intermediate-acting insulin, known as neutral protamine hagedorn or NPH insulin. NPH insulin only becomes active around 1 to 2 hours after administration, with a peak effect after 4 hours, and lasts for 16 to 24 hours.

Moving on, we have the long-acting insulins, which include insulin glargine and detemir. Once administered, glargine forms a precipitate at the injection site before it’s slowly released into the bloodstream, while detemir binds to albumin in the blood for a time before dissociating and becoming active.

This accounts for their delayed onset of action, which is between 1 to 2 hours of administration, as well as their long duration.

In addition, these medications do not have a peak effect. Detemir typically lasts for around 20 hours, whereas glargine can last for up to 24 hours.

Finally, ultra long acting insulin is a relatively new preparation called insulin degludec. Degludec is a depot injection, meaning the medication is deposited beneath the skin and slowly releases insulin into the blood.

Its onset of action is between 1 to 2 hours with no peak effect, and its duration of action can last up to 48 hours.Now, one of the most commonly used insulin regimens is the basal-bolus insulin regimen, in which a basal insulin like intermediate-, long-, or ultra long- acting insulin is given before bed to maintain fasting blood glucose levels, and a bolus of a rapid- or short-acting insulin is given before meals to control postprandial glucose levels.

Typically a client would need roughly 3 injections of a bolus insulin, as well as 1 or 2 injections of a basal insulin. Now, to offer a simpler regimen with fewer injections per day, intermediate-acting insulin is usually pre-mixed with a rapid-acting or regular insulin in one syringe or pen.

This combination is typically taken only two times a day, before breakfast and before dinner.Once administered, insulin binds to its receptors on the surface of the cell membrane on the insulin-responsive tissues like muscle cells and adipose tissue, and facilitates their uptake of glucose from the blood.

In addition, insulin acts on the liver and muscles to promote glycogenesis, which is the storage of glucose as glycogen.

In the liver and adipose tissue, insulin also stimulates lipogenesis, or the synthesis of fatty acids and triglycerides; while in muscles, it also promotes amino acid uptake and protein synthesis.

On the flip side, insulin inhibits the breakdown of glycogen, lipids and proteins in these tissues. Finally, insulin activates the sodium potassium ATPase pumps, which shift potassium into the intracellular space, thereby decreasing potassium levels in the blood.Now, the main side effect of insulin therapy arises when too much insulin is administered, leading to hypoglycemia.

This is more common with insulins that have a peak effect. Some symptoms of hypoglycemia include headache, dizziness, anxiety, tachycardia, sweating, hunger, and weakness.

In addition, repeated insulin injection at the same area can lead to lipodystrophy, where there’s an atrophy or hypertrophy of the subcutaneous fat.

This presents either as a skin depression or a raised skin lump, respectively. Some clients may also develop anaphylactic reactions.Now, insulin is contraindicated in clients who have hypoglycemia, which would be exacerbated.

Caution should be taken in clients who are at higher risk of hypoglycemia, such as elderly clients, those with persistent vomiting, or diarrhea, as well as clients with hepatic or renal disease.

Finally, precaution should be taken in clients with a fever, infection, or undergoing surgery, as they should receive a higher dose of insulin to prevent the development of complications like diabetic ketoacidosis or hyperglycemic hyperosmolar nonketotic coma.

Now, when a client with type 1 diabetes mellitus is prescribed insulin, first perform a focused baseline assessment of your client, including their current weight and recent weight loss, as well as polyphagia and polyuria.

Then, review their most recent laboratory test results, including blood glucose, hemoglobin A1C, as well as renal and hepatic function, and urinalysis.

If you're administering insulin intravenously, be sure to review their blood potassium level as well. Next, explain to your client how their medication will help to maintain their blood glucose levels within a normal range.

In addition, explain how they should also adhere to an individualized antidiabetic regimen, including frequent glucose monitoring, regular activity, and a low-carbohydrate and high-fiber diet.

Demonstrate the correct method of checking their blood glucose level, how often they should check it, and how to manage their glucose levels throughout the day with insulin, meals, snacks, and activity.

Now, if they get sick and are not eating as much as usual, be sure they understand how they need to continue to monitor their blood glucose at least every 3 to 4 hours and to follow their prescribed sick-day plan.

Advise your client to store unopened vials of insulin in the refrigerator, while the insulin vial currently in use can be kept at room temperature away from heat or direct sunlight.

Lastly, advise them to wear medical alert identification at all times. Regarding self-administration of insulin, be sure to teach your client how to draw up their insulin or operate their insulin pen, and show them the preferred injection sites, including the posterior arm, abdomen, and thigh.

Stress the importance of changing their injection sites regularly and inspecting the area for bruising, broken skin, or tenderness before administration, and teach them to avoid any area that feels numb, lumpy, or unusually firm.

Make sure that your client is able to correctly self-administer their insulin using proper technique.Next, ensure your client understands how to recognize and manage symptoms of hypoglycemia, such as hunger, fatigue, tremors, headache, dizziness, and confusion; if these occur, stress the importance of checking their blood glucose level, followed by consuming about half a cup of fruit juice, three glucose tablets, or approximately 15 grams of sugar; and to check their blood glucose again 15 minutes later.

Also, review the symptoms of hyperglycemia, including fatigue, blurred vision, as well as increased thirst, appetite, and urination.

Caution them about the symptoms of diabetic ketoacidosis, which include an extremely high blood glucose level, as well as nausea, fruity-scented breath, dry mouth, excessive thirst, frequent urination, drowsiness, or confusion, and advise them to seek medical assistance right away if these symptoms develop.

Now, when administering regular insulin intravenously in an acute care setting, be sure to verify with a second nurse the insulin dosage against the prescribed order.

Then, adjust the infusion rate based on the prescribed protocol, and keep a close eye on your client’s blood glucose and potassium level, as well as for symptoms of hypoglycemia.Finally, when caring for a client who is prescribed insulin, monitor for side effects and evaluate for the therapeutic effect of improved glucose control and decreased symptoms of hyperglycemia.

All right, as a quick recap… Insulin is a medication used to treat clients with diabetes mellitus. There are five main categories of insulin, based on their onset of action and duration of effect.

These include rapid-acting, short-acting or regular, intermediate-acting, long-acting, and ultra long-acting insulins. Once administered, insulin binds to its receptors on the surface of the cell membrane on insulin-responsive tissues and facilitates their uptake of glucose from the blood.

Insulin also acts on the liver and muscles to promote glycogenesis. The main side effect of insulin is hypoglycemia, which can result in hunger, fatigue, tremors, headache, dizziness, and confusion.

When caring for a client who is prescribed insulin, nursing considerations include performing a focused baseline assessment, monitoring for side effects, and evaluating the effectiveness of therapy.

Finally, client teaching is focused on safe self-administration, combined with lifestyle modifications based on an individualized antidiabetic regimen, and how to recognize and manage side effects like hypo-