PATIENT SAFETY
October 21, 2025

Strategies to Prevent Fivefold Wrong Dose Errors With U-500 Insulin

​​​Author Biography
Myungsun Ro, PharmD, MS, Data Science and Research Team, Patient Safety Authority
​Myungsun (Sunny) Ro ( mro@pa.gov) is a research scientist on the Data Science & Research team at the Patient Safety Authority (PSA). Her responsibilities include analyzing and synthesizing data from various sources to identify opportunities to improve patient safety, as well as writing scientific articles for publication in the PSA’s peer-reviewed journal, Patient Safety.

Abstract

Over the years, the Patient Safety Authority (PSA) has highlighted numerous errors involving insulin.1–5 Recently, PSA has received several reports via the Pennsylvania Patient Safety Reporting System (PA-PSRS) describing errors with U-500 insulin that led to patients receiving either five times less or five times more insulin than intended. Humulin R U-500, a type of insulin that is five times more concentrated than U-100 insulin, is used to manage blood glucose levels in individuals with diabetes mellitus requiring more than 200 units of insulin per day.6,7 As a high-alert medication,8 U-500 insulin has been associated with dose errors that can lead to life-threatening hypoglycemia or hyperglycemia.6

Keywords
mededication error, medication safety, patient safety, concentrated insulin, insulin overdose, insulin underdose, Humulin R U-500

References

  1. Patient Safety Authority. Complexity of Insulin Therapy. Pa Patient Saf Advis. 2005;2(2):30-31.
  2. Patient Safety Authority. Medication Errors With the Dosing of Insulin: Problems Across the Continuum. Pa Patient Saf Advis. 2010;7(1).
  3. Patient Safety Authority. Overdoses Caused by Confusion Between Insulin and Tuberculin Syringes. Pa Patient Saf Advis. 2004;28:1-2.
  4. Patient Safety Authority. The Current State of “Wrong Patient” Insulin Pen Injections. Pa Patient Saf Advis. 2015;12(3):110-115.
  5. Patient Safety Authority. Treating Hyperkalemia: Avoid Additional Harm When Using Insulin and Dextrose. Pa Patient Saf Advis. 2017;14(3).
  6. National Library of Medicine. Label: HUMULIN R U-500 - Insulin Human Injection, Solution. Dailymed. February 22, 2024. Accessed April 1, 2025. https:/​/​dailymed.nlm.nih.gov/​dailymed/​drugInfo.cfm?setid=b60e8dd0-1d48-4dc9-87fd-e14675255e8c
  7. American Diabetes Association Professional Practice Committee. 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes—2025. Diabetes Care. 2024;48(Supplement_1):S181-S206. doi:10.2337/​dc25-S009
  8. Institute for Safe Medication Practices. ISMP List of High-Alert Medications in Acute Care Settings. 2024. https:/​/​www.ismp.org/​sites/​default/​files/​attachments/​2024-01/​20240111.pdf