What is the proper protocol for administering insulin infusion to a patient?

How to Give Insulin Infusion

Preparation and Setup

Prepare insulin infusions at a standardized concentration of 1 unit/mL using regular human insulin in 0.9% normal saline, and prime the tubing with 20 mL of waste volume before connecting to the patient. 1

• Use only regular human insulin for IV administration - other insulin formulations (aspart, glargine, NPH) cause unpredictable pharmacokinetics and are contraindicated for intravenous use 1
• The 1 unit/mL concentration minimizes dosing errors and allows consistent titration across all critically ill patients 1
• Priming with 20 mL waste volume is essential because insulin adsorbs to IV tubing material initially, and without priming you will underdose the patient from the start 1

Clinical Indications for IV Insulin

Use IV insulin infusion for hemodynamically unstable patients requiring vasopressors, all patients with type 1 diabetes in critical care, and any situation requiring rapid titration for tight glycemic control. 1

Specific Dosing Protocols:

• For diabetic ketoacidosis (DKA): Start at 0.1 units/kg/hour as continuous infusion only after confirming serum potassium is adequate (>3.3 mEq/L) 1
• For general critical care hyperglycemia: Start at 0.5-1 unit/hour with titration based on hourly glucose monitoring 1

Glucose Monitoring During Infusion

Measure blood glucose hourly using point-of-care testing during active titration, targeting 140-180 mg/dL in critically ill patients. 1

• This target range balances glycemic control against hypoglycemia risk 1
• Evaluate the amount and timing of carbohydrate intake when calculating insulin requirements and adjust protocols accordingly 1

Transitioning to Subcutaneous Insulin

Administer subcutaneous basal insulin 2 hours before discontinuing the IV infusion to prevent rebound hyperglycemia. 1

Transition Criteria (all must be met):

• Glucose levels stable <180 mg/dL for 24 hours 1
• Oral feeding has resumed 1
• Peripheral edema has resolved 1
• Patient is off vasopressors 1

Calculating the Subcutaneous Dose:

• Calculate the basal insulin dose based on the IV insulin infusion rate during the last 6 hours when stable glycemic goals were achieved 1
• Give the subcutaneous basal insulin 2 hours before stopping the IV infusion to allow adequate absorption and prevent hyperglycemic rebound 1

Common Pitfalls to Avoid

• Never use insulin analogs (aspart, lispro, glargine, detemir) for IV infusion - only regular human insulin has predictable IV pharmacokinetics 1
• Never skip the tubing prime - the first 20 mL of insulin solution will be absorbed by the tubing, resulting in significant underdosing 1
• Never transition to subcutaneous insulin without the 2-hour overlap - this consistently causes rebound hyperglycemia requiring reinitiation of IV insulin 1
• Never transition while the patient is still hemodynamically unstable - subcutaneous absorption is unpredictable in patients with poor perfusion or on vasopressors 1