When to use a VRIII and what to do with the usual insulin?

Please see the full VRIII guideline for additional information. 

Variable Rate Intravenous Insulin Infusion (VRIII)

Consider VRIII in: 

• A patient with type 1 diabetes who is: 
  • Nil by mouth 
  • Has prolonged vomiting 
  • Reduced consciousness. 
• Any diabetic patient:
  • With uncontrolled hyperglycaemia (significantly outwith specified targets) 
  • Who is peri-operative and unlikely to be eating.

Management of usual insulin while using VRIII

• Continue long-acting insulin alongside VRIII e.g. Humulin® I, Insulatard®, Lantus®, Levemir®, Abasaglar® or Tresiba®. 
• Pre-mixed or fast-acting insulin should not be administered whilst on VRIII e.g. Humulin® M3, Novomix® 30, HumalogMix® 25, HumalogMix® 50.  
• Do not convert mixed insulin to long-acting component only with a VRIII e.g. Humulin® M3 should not be given as Humulin® I.  
• In patients with type 2 diabetes, usual diabetes medications can be continued with a VRIII unless other contraindications e.g. acute kidney injury. 

Guideline reviewed: February 2025

Page updated: November 2025