Insulin Update: Just the Facts

Research has shown        that tight glycemic control is beneficial to all patients in hospital, speeding up recovery and producing positive outcomes. The use of insulin during hospitalizations has increased, (including temporary use with non-diabetic patients). The variability of types of insulin available has increased since the development of synthetic products more than 30 years ago. Nurses need to be aware of the various types of insulin that are available, and how they work.

Rapid-Acting Insulin
Rapid-acting insulins are most commonly used with hospitalized patients. They are based on sliding scales to quickly correct blood sugar levels or provide coverage during meals. Short-acting insulins were previously common in hospitals, but have a longer onset than the rapid-acting variety. Intermediate-acting insulins are used in combination with rapid or short-acting insulin. The intermediate category provides coverage for approximately half a day. The long-acting insulins provide a basal coverage for about a day.

Rapid-acting insulin includes ®). The onset of action for these rapid-acting insulins is between 10-30 minutes, with a peak action time range of 30-90 minutes after administration. These insulins last for about 1-5 hours, depending on the brand used. Rapid-acting insulin acts by rapidly correcting hyperglycemia, and are designed for mealtime coverage. Thus patients must eat immediately after administration. Rapid-acting insulin should be used together with long-acting insulin to provide better hyperglycemic control.

Short- and Intermediate-Acting Insulin
Short-acting insulin is Regular (R) insulin  ). The onset of action is 30 min -1 hour, and the peak action time is 2-5 hours after administration. Regular insulin lasts for about 5-8 hours and provides coverage for meals consumed within 30-60 minutes after administration. The “R” with the insulin name helps identify it as Regular.

Intermediate-acting insulin includes NPH (N) and  (L) insulin. The onset of action is between 1-2 hours, and levels peak 3-12 hours after administration. The duration of action is between 18-24 hours. This type of insulin provides coverage for up to half a day or overnight, and is usually used in combination with rapid or short-acting insulin. If the insulin has an “N” in the brand name, this indicates it is NPH.

Long-Acting Insulin
Long). This insulin group has an onset of action between 1-2 hours and a peak action time that varies between 6-20 hours. Note that Lantus® does not peak, but provides a steady level of insulin throughout the duration time. Total duration of action is anywhere between 20-36 hours. Long-acting insulin provides basal coverage for about a day, and is usually used in combination with rapid or short-acting insulin. Also note that Lantus® cannot be mixed with any other insulin, and should be injected in a separate site.

It used to be common to have a patient with short-acting and intermediate-acting insulin. Treatment has shifted to using rapid-acting and long-acting insulin for patient therapy to address both immediate and daily insulin needs. Mixed insulins are combinations to provide daily insulin coverage; these should be reviewed prior to administration.

For more information on insulin and diabetes, the American Diabetes Association (ADA) is a good resource for nurses, patients and families. Two diabetes courses are available at Diabetes Overview is a general course that includes information about Type 1, Type 2 and Gestational Diabetes; An Overview of Patient Management Issues in Type 2 Diabetes covers new treatment modalities, an overview of management principles, blood glucose monitoring devices, an overview of insulin administration and the use of oral hypoglycemic drugs.

American Diabetes Association. (2011). Insulin basics. Retrieved from

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