Insulin and Medication Errors

Pharmacy TimesOctober 2009
Volume 75
Issue 10

Ms. Hall is a clinical assistant professor at the University of Oklahoma Health Sciences Center, College of Pharmacy. Dr. Armor is a clinical assistant professor at the University of Oklahoma Health Sciences Center, College of Pharmacy. Both are certified diabetes educators.

Insulin is included on the Institute for Safe Medication Practices List of High-Alert Medications.1 Medications appearing on this list represent increased risk of causing significant harm if used in error. Special safeguards to reduce the risk of errors associated with these drugs are recommended, including strategies such as improving access to information about the drugs, standardized ordering, storage, and administration of them, and automated or independent double-checks to verify appropriate administration.1

This article summarizes commonly prescribed insulin products and medication errors encountered in an outpatient diabetes clinic. Managing diabetes with insulin is challenging for patients; therefore, sustained, ongoing support from a health care team is essential. In an effort to raise awareness among health care providers about insulin, case scenarios illustrating common errors and easily overlooked opportunities for educating patients are presented.


In comparison with regular insulin, rapid-acting insulin analogs have a more rapid onset of action and shorter duration of action, reaching higher peak levels and achieving their peak much closer to injection time. They are designed to be administered 10 to 20 minutes before mealtimes.

When compared with Neutral Protamine Hagedorn, basal insulin analogs have a prolonged duration of action without a pronounced peak. Premixed insulin analogs are single-peak insulin containing a portion of rapid-acting insulin for meal coverage, plus a protamine suspension of the respective insulin analog for basal coverage (eg, aspart 70/30 contains 30% aspart and 70% aspart protamine suspension). In contrast, premixed human insulin (eg, Humulin 70/30) has 2 distinct peaks.2 All of the insulin analogs may be used in a pen-type delivery device.

Medication Errors

Apidra (glulisine), a rapid-acting insulin with a more rapid onset of action and shorter duration of action than regular human insulin, and Lantus (glargine), the 24-hour basal insulin indicated for once-daily subcutaneous administration, are made by sanofi-aventis. The packaging of Apidra and Lantus are very similar and can lead to medication errors.

The difference between the 2 packages is the wording and the color of the labels. Apidra labels are blue; Lantus labels are purple. Patients have administered large doses of Apidra thinking they were administering a basal dose of Lantus. For safety, advise patients to label the bottles with different colored marking pens. Another recommendation is to store the 2 insulin products in different areas of the refrigerator.

NovoLog, NovoLog Mix 70/30, and Novolin 70/30 have similar names and can be confusing for both patients and health care professionals. This confusion increases the risk for medication errors. NovoLog Mix 70/30 is sometimes referred to as simply “NovoLog Mix” but not to be confused with “NovoLog,” which refers to insulin aspart. Moreover, when filling premixed insulin prescriptions, note whether the order reads NovoLog or Novolin, indicating the need for analog insulin or human insulin, respectively.

Continuous subcutaneous insulin infusion (CSII) pumps use rapid-acting insulin analogs or, in rare cases, U-500 Regular. One pump user filled a NovoLog prescription and received NovoLog Mix 70/30 by mistake. CSII pumps administer rapid-acting insulin in very small amounts over a 24-hour period as well as in bolus amounts at mealtimes. In this way, the rapid acting insulin acts as both a basal (background) and bolus (mealtime) insulin. An error involving administering basal or premixed insulin via CSII could potentially be fatal.

CSII pump users should be receiving insulin for the pump in 10-mL standard vials. The pump user will fill the reservoir (typically a 3-cc syringe) with insulin from vials and then place the reservoir into the pump. Recently, a patient using the pump for the first time was dispensed insulin pen-fill cartridges rather than vials. Although the correct insulin type was dispensed, the dosage form of pen-fill cartridges do not fit inside the insulin pump, as the pharmacist believed. To avoid wasting the pen-fill insulin, in this scenario, the reservoir was filled with the pen-fill cartridges, and a new prescription was written for vials.

Administration Errors

Short insulin syringes are ideal for individuals who are thin. A person with a large girth administering insulin via a short needle may not be administering into the subcutaneous space, however, and therefore may not receive adequate insulin absorption. Recently, an obese patient with type 2 diabetes requiring frequent increases in both basal and bolus insulin was evaluated. He was injecting with a short needle for glargine and Mini (5 mm) pen needle for aspart. The patient reported that the 90 units of basal insulin caused a raised circular area under his skin. Once both his syringe and pen needles were corrected to standard ½-inch length needles, his glycemic control improved.

Review syringe technique with persons new to administering insulin. A newly diagnosed patient with type 1 diabetes presented to the diabetes clinic soon after a hospital discharge for diabetic ketoacidosis. His blood glucose (BG) was under control after correct administration of basal and rapid-acting insulin. Hospital nurses taught him insulin administration. He was referred to the diabetes clinic for outpatient management. The first outpatient visit revealed his BG was running very high. After administration of a dose of rapid- acting insulin in the clinic, his BG responded well. He demonstrated an understanding of the insulin regimen and voiced understanding of how to administer his injections.

At his next visit to the clinic, his BG was >400. He reported that he had not been eating much food because his BG levels had been very high, and it seemed that the insulin was not working. Again, the insulin regimen and storage of insulin was reviewed, and he was reportedly giving the correct amount of insulin at the correct time. When asked to administer a dose of rapid-acting insulin in the office, a problem with his technique was identified: he had been injecting air. His technique revealed that he was drawing up the correct dose of air into the syringe, inserting the syringe into the vial, turning the vial upside down and then waiting for the insulin to fill up the air pocket in the syringe. After he was taught and he practiced the proper technique for injecting insulin, his BG control greatly improved. He said he was taught the proper injection technique in the hospital, but because there was so much going on, he had forgotten.

Basal insulin products like insulin glargine and insulin detemir should not be mixed with any other insulin products.3 One patient reported taking his insulin glargine in the evening via syringe and then reusing the glargine syringe the following morning to take his rapid-acting insulin. In addition to needle reuse, he was essentially mixing his insulin products.

Needle reuse can bend or dull the tip. It increases pain at the injection site and could cause the needle to break off and become lodged in the skin. In addition, it increases the risk of infections at the injection site.4

Ways to reduce pain at injection sites include4:

• Review injection technique with a health care professional.

• Allow alcohol from a swab to completely dry on skin before injecting.

• Inject insulin at room temperature.

• Do not reuse needles.

• Penetrate the skin quickly. Consider an injection device if this is hard to do.

• Speak with a health care professional about using a different needle size.

• If taking large doses, speak with a physician about splitting the dose to twice daily.

Insulin Storage

If stored in a refrigerator, unopened vials of insulin are good until the expiration date printed on the bottle. Once opened, insulin in a vial generally lasts for 1 month, whether stored at room temperature (59-86°F) or in a refrigerator. A bottle is considered open if the seal has been punctured. Write the date that you opened the bottle on the bottle’s label.4 With insulin pens and their cartridges, storage life varies from 7 days to 1 month.

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