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ISMP: Why Are Insulin Medications So Prone to Error?

May 4, 2014

From The Institute For Safe Medication Practices: Insulin accounts for more than 10% of all drug mistakes. This drug class has been rated as having the most mistakes every year for the last 20 years.

When the Pennsylvania Patient Safety Authority did a study of state hospitals focusing on medication errors, they found that errors in dispensing insulin were the most frequent of all medication mistakes made. Twenty percent of patients were given the wrong kind of insulin from the pharmacy; 18.4% were supplied with the wrong mix of insulins; and 17.4% of the mistakes were due to the misreading of prescriptions.

What they discovered is that one of the reasons for the error rate seems to be due to simple confusion….

We now have 13 different types of insulin and they are available in five different categories which are:

  • Premixed
  • Long-Lasting
  • Intermediate Acting
  • Short Acting
  • Rapid Acting

Another reason is the number of different but similar names such as:

  • Humalog
  • Humulin
  • Novolog
  • Novolin


Now over the next few years we can expect to see at least 3-6 more unique insulin’s that could be slower in action, more rapid onset, longer acting and many more combinations. This will continue to add to the number of mistakes when using insulin. 

Example of how easy it is to make an error using insulin:

The physician wrote an order for "Novolin 18 units bid." The order was not clarified when taken off, and regular insulin was given for two doses. When the physician came in the following day, the order was clarified, and he ordered Novolin N insulin. The patient was given two doses of Novolin R. Where was the mistake made? It is never because of just one issue. It is always a series of errors in the processes of filling and dispensing a prescription. See example 1


Many of these errors can be very dangerous and could cause death, leading to legal action and higher insurance rates.

When ever getting a prescription for an insulin product you should be double checking to make sure the patient gets exactly what the prescription calls for and that the prescription is correct.

Next week we will share with you, "How To Prevent Insulin Errors"