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Insulin is used to treat people who have diabetes. Each type of insulin acts over a specific amount of time. The amount of time can be affected by exercise, diet, illness, some medicines, stress, the dose, how you take it, or where you inject it. The table below is a general guide. Your results may be different.
Insulin strength is usually U-100 (or 100 units of insulin in one milliliter of fluid). Short-acting (regular) insulin is also available in U-500. This is five times more concentrated than U-100 regular insulin. Long-acting insulin (glargine) is also available in U-300. This is three times more concentrated than U-100 long-acting insulin. Be sure to check the concentration of your insulin so you take the right amount.
Insulin is made by different companies. Make sure you use the same type of insulin consistently.
When it starts to work (onset)
The time of greatest effect (peak)
How long it lasts (duration)
Rapid-acting insulins work over a narrow, more predictable range of time. Because they work quickly, they are used most often at the start of a meal. Rapid-acting insulin acts most like insulin that is produced by the human pancreas. It quickly drops the blood sugar level and works for a short time. If a rapid-acting insulin is used instead of a short-acting insulin at the start of dinner, it may prevent severe drops in blood sugar level in the middle of the night.
Apidra (glulisine), Humalog (lispro), Novolog (aspart)
30 minutes–3 hours
Rapid-acting insulin also comes in a form that can be inhaled through the mouth.
Afrezza (insulin human, inhaled)
Contained in a cartridge
Short-acting insulins take effect and wear off more quickly than long-acting insulins. A short-acting insulin is often used 30 minutes before a meal so that it has time to work. These liquid insulins are clear and do not settle out when the bottle (vial) sits for a while.
Humulin R, Novolin R (insulin regular)
4–12 hours (U–100), Up to 24 hours (U–500)
Intermediate-acting insulins contain added substances (buffers) that make them work over a long time and that may make them look cloudy. When these types of insulin sit for even a few minutes, the buffered insulin settles to the bottom of the vial.
Humulin N, Novolin N (insulin NPH)
Long-acting insulins have no peak and last for up to 24 hours.
Lantus (glargine), Levemir (detemir)
Up to 24 hours
Ultra Long-acting insulins have no peak and last for 24 hours or more.
Toujeo (glargine U–300), Tresiba (degludec U-100 and U–200)
6 hours (glargine), 1 hour (degludec)
24 hours or more (glargine), 42 hours or more (degludec)
Mixtures of insulin can sometimes be combined in the same syringe, for example, intermediate-acting and rapid- or short-acting insulin. Not all insulins can be mixed together.
For convenience, there are premixed rapid- and intermediate-acting insulin. The insulin will start to work as quickly as the fastest-acting insulin in the combination. It will peak when each type of insulin typically peaks, and it will last as long as the longest-acting insulin. Examples include:
Other Works Consulted
Insulin degludec injection (2015). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/MonoDisp.aspx?monoid=fandc-hcp19982&book=DFC&fromtop=true&search=580363%7c24&isStemmed=True&asbooks=. Accessed December 30, 2015.
Insulin detemir injection (2014). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp14499§ions. Accessed May 13, 2015.
Insulin glargine (rDNA origin) injection (2015). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp12721§ions. Accessed May 13, 2015.
Insulin glulisine (rDNA origin) injection (2014). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp13023§ions. Accessed May 13, 2015.
Insulin isophane (NPH)/insulin regular injection (2013). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp12321§ions. Accessed May 13, 2015.
Insulin isophane injection (2014). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp12320§ions. Accessed May 13, 2015.
Insulin lispro injection (2014). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp12722§ions. Accessed May 13, 2015.
Insulin regular (human) inhalation (2015). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp19696§ions. Accessed May 13, 2015.
Insulin regular (human) injection (2015). Facts and Comparisons eAnswers. http://online.factsandcomparisons.com/PrintMonoDisp.aspx?id=fandc-hcp12645§ions. Accessed May 13, 2015.
Current as of:
December 20, 2019
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineKathleen Romito MD - Family MedicineAdam Husney MD - Family MedicineDavid C.W. Lau MD, PhD, FRCPC - EndocrinologyRhonda O'Brien MS, RD, CDE - Certified Diabetes Educator
Current as of: December 20, 2019
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine & David C.W. Lau MD, PhD, FRCPC - Endocrinology & Rhonda O'Brien MS, RD, CDE - Certified Diabetes Educator
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