Correction Doses of Insulin (PRN insulin)
- Aim for target Capillary Blood Glucose (CBG) 6-10mmol/L (unless specified otherwise).
- Avoid using correction doses where possible - review, identify causes and amend patient's regimen instead.
- Use Novorapid® for PRN correction doses. Actrapid® should not be used.
- As a guide, 1 unit of Novorapid® will reduce the CBG by 3mmol/L - see table 1 for suggested doses.
Table 1 - Suggested correction doses of Novorapid®
| CBG (mmol/L) |
PRN Novorapid® dose |
| 18 - 20 |
2 units |
| 20 - 24 |
4 units |
| >24 |
6 units |
- Re-check CBG after 2 hours. If >18mmol/L repeat PRN dose.
- Avoid repeat PRN doses, particularly overnight, due to risk of insulin 'stacking' and hypoglycaemia. Aim to adjust usual insulin instead.
Guideline reviewed: February 2025
Page updated: November 2025
