How to switch between insulins?

This note will discuss how to switch between insulins?
Abdelwahab Ward, BS Pharm, PharmD

Switching insulins should always be done with prescriber approval and close monitoring. Advise patients to closely monitor blood glucose levels after switching insulins. In most cases, the number of units per day stays the same when you switch insulins with a similar onset and duration of action. But sometimes the timing and frequency of administration varies. Common scenarios to help you make switches...

  • NPH (Insulatard) to long-acting (Lantus, Levemir): Use the same number of units when switching NPH to Levemir (detemir) or ONCE-daily NPH to Lantus.
    • But for patients switching from TWICE-daily NPH to once-daily Lantus (glargine), recommend reducing the daily dose about 20% to decrease the risk of hypoglycemia.
  • Long-acting to long-acting: Use the same daily dose when switching between Lantus and Levemir.
    • Keep in mind that Levemir, and sometimes Lantus, may need to be given twice daily instead of once daily to maintain glycemic control.
  • Regular (Actrapid) to rapid-acting (Novorapid, Apidra): Keep the number of units the same, but recommend different timing around meals due to their different onset.
    • Tell patients to use regular insulin about 30 min before meals, and rapid-acting (Novorapid, etc) about 10 min before or with meals.
    • After the initial conversion, have patients monitor their blood glucose more frequently and help them fine-tune their insulin dose.
  • Mixtard 70/30 to Lantus or Levemir: Add up the total units for each dose and give 70% to 75% as long-acting insulin (once daily or divided twice daily [insulin detemir]) or reduce dose by 20%.
    • Give 25% to 30% of each premix dose as prandial insulin (regular or rapid-acting analog) before the meals before which the premix was usually taken.

References

  1. How to Switch between Insulin Products (samuelmerritt.instructure.com, 2009). [online] Available at: https://samuelmerritt.instructure.com/courses/1181923/files/45370846/download.
  2. DEFA Diabetes for All. (2021). Information for Health Care Professionals: Insulin Switching Guide (English). [online] Available at: https://www.diabetesdefa.org/assets/document/information-health-care-professionals-insulin-switching-guide-english.
Abdelwahab Ward, BS Pharm, PharmD