Management of a patient with type 2 diabetes who is 'nil by mouth'

• Increase the frequency of blood glucose monitoring. 
• Withhold all oral diabetes drugs and GLP-1 agonists. 

Also consider the following: 

• If using insulin, consider dose-reduction to avoid hypoglycaemia (10-20%).
• Withhold short / rapid-acting insulin. 
• Consider changing twice daily mix insulin (e.g. Humulin® M3) to intermediate-acting (e.g. Humulin® I) at 50-70% total daily dose.
• If very unwell and / or erratic capillary blood glucose (CBG) profile, consider Variable Rate Intravenous Insulin Infusion (VRIII). 

Guideline reviewed: February 2025

Page updated: November 2025