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Types of Insulin

Nursing Knowledge

Types of Insulin

Insulin is a hormone produced by the pancreas that regulates blood glucose levels. It is used to treat diabetes mellitus, a chronic condition that occurs when the body cannot produce enough insulin or use it effectively. There are different types of insulin available, each with varying onset times, peak times, and durations. Understanding the different types of insulin and how each works is essential for nurses caring for clients with diabetes and can help individuals with diabetes better manage the condition.

Last updated: September 21, 2026

What is insulin?

Insulin is a hormone produced by the pancreas that regulates blood sugar levels. It allows cells to take in glucose for energy and signals the liver to store excess glucose. It is crucial in maintaining stable blood glucose and is centrally involved in diabetes if the normal function is impaired.

What is insulin used for?

Insulin is used for the treatment of diabetes mellitus, a condition in which the body does not produce enough insulin or cannot use it effectively (insulin resistance), or is resistant to it, resulting in high blood sugar levels. Insulin therapy aims to mimic the body’s natural pattern of insulin release, which is a steady low level of insulin release throughout the day with spikes during meal times. This helps to keep blood glucose levels within the normal range, preventing the symptoms of high blood sugar and reducing the risk of diabetes complications.

What are the different types of insulin?

There are several different types of insulin, classified by the onset and the duration of the insulin. Here are the main categories:

Rapid-acting insulin: starts to work within approximately 15 minutes after injection and peaks in about 1 to 3 hours, continues to work for 3 to 5 hours
Short-acting insulin: starts to work within approximately 30 minutes after injection and peaks at 2 to 4 hours, continues to work for 5 to 8 hours
Intermediate-acting insulin: starts to work within approximately 1 to 4 hours after injection and peaks in 4 to 8 hours, continuing to work for 12 to 18 hours
Long-acting insulin: starts to work several hours after injection and works for about 24 hours
Ultra-long-acting insulin: starts to work in approximately 2 to 4 hours after injection and the duration can extend beyond 40 hours, there is no peak effect
Pre-mixed insulin: combination of 2 different types of insulin: one that controls blood sugar at meals and another that controls blood sugar between meals

How is insulin delivered?

Insulin can be delivered through subcutaneous injection (syringes, pens, pumps), inhalation, and/or intravenously (IV). Only regular insulin, insulin aspart, insulin lispro, and insulin glulisine are approved for IV administration. Long-acting, intermediate-acting, and premixed insulins must never be given IV.

What are some clinical tips for managing diabetes with insulin?

Clinical tips for managing diabetes with insulin include testing glucose levels according to provider instructions and avoiding meal delays after injection or skipping meals to avoid hypoglycemic events.

Critical Safety Points:

Recognition and treatment of hypoglycemia using the “Rule of 15” is recommended (i.e. 15 g fast-acting carbohydrate, recheck in 15 minutes).
Unopened vials of insulin should be refrigerated; opened vials may stay at room temperature for up to 28 days for most formulations.
NPH Insulin should be gently rolled/mixed before use.
Clear insulins should not be used if cloudy.
Patients and clinicians should use injection site rotation to prevent lipodystrophy.
Use of continuous glucose monitoring (CGM) devices are important in hypoglycemia prevention.

What is the onset time for rapid-acting insulin?

The onset time for rapid-acting insulin typically ranges from 15 to 30 minutes.

How does glucagon affect blood sugar levels?

Glucagon stimulates gluconeogenesis (new glucose production) which is dependent on adequate hepatic glycogen stores to raise blood sugar levels. In patients who are malnourished, glucagon may be less effective.

How should insulins be mixed when using both regular and NPH insulins?

Insulin mixing refers to drawing up two types of insulin (for instance, a short-acting and an intermediate-acting insulin) into the same syringe for injection, which can help simplify the injection process.

Always mix insulins in the appropriate order: Regular insulin should be drawn up first (clear), followed by NPH (cloudy). Do not mix long-acting insulins (e.g., glargine or detemir) with other insulins.

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Types of Insulin

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