Large-Scale Insulin Overdoses From Syringe-Related Errors: Analysis and Insights Across 47 Hospitals

Background Insulin is a high-alert medication associated with numerous medication errors. We sought to analyze syringe-related issues which we defined as the use or selection of a syringe during insulin preparation, dispensing, or administration that contributed to, or had the potential to contribute to, a dosing error or discrepancy. Methods A retrospective mixed-methods study was conducted using Medication Error event reports from the Pennsylvania Patient Safety Reporting System (PA-PSRS) from 2015 to 2024. A targeted query identified reports involving U-100 insulin and syringe-related issues resulting in dosing errors or near misses. Structured and free-text data were coded for variables such as clinical indication, route of administration, wrong dose ratio, syringe size, and contributing factors. Results Seventy-four reports across 47 facilities met inclusion criteria. Serious events accounted for over one-third of errors that reached the patient. Tenfold overdoses were most frequent, occurring in 56.4% of reports with a wrong dose ratio, followed by hundredfold overdoses in 20.0%. Reports from the emergency department care area group had the highest frequency of tenfold overdoses, while intensive care unit reports had the greatest proportion of hundredfold overdoses. More than 97% of wrong dose errors that reached the patient resulted in an overdose of tenfold or greater. Among reports specifying syringe volume, 73.8% involved a 1-milliliter syringe; 95.2% of overdoses in these reports were exactly tenfold. Contributing factors included improper syringe storage, similar appearance, and lack of provider experience. Variability in hospital insulin protocols and formularies was also observed. Conclusion Syringe-related issues present a serious and preventable threat to patient safety. Facilities are encouraged to evaluate their insulin protocols and adopt strategies to prevent and mitigate patient harm associated with syringe-related issues. Plain Language Summary Although insulin is used daily by millions of people around the world, it is considered a high-alert drug that has been associated with more medication errors than any other medication type or class. One challenge in administering insulin is that it is measured in “units” rather than milliliters (mL), requiring unique insulin syringes with the appropriate markings. Using a syringe intended for other medication to administer insulin could lead to an overdose of up to 100 times the intended dose. To identify contributing factors and develop strategies to reduce the risk of wrong dose errors related to the use or selection of syringes, researchers focused on event reports submitted by Pennsylvania facilities over the last decade that involved U-100 insulin and syringe-related issues resulting in dosing errors or near misses. Some of the key takeaways of their detailed study—which encompassed 74 reports from 47 facilities—are that over a third of errors that reached the patient were serious events and among reports specifying syringe volume, 73.8% involved a 1-mL syringe. Contributing factors included using the wrong syringe due to improper syringe storage, similar cap color or packaging, and provider’s lack of experience. Variability in hospital insulin protocols and formularies was also observed. The authors encourage facilities to evaluate and standardize their existing insulin protocols and formularies, and implement the suggested safety strategies for preventing syringe-related insulin dose errors.