What is the recommended dosage of intravenous (IV) insulin for post-operative patients?

Dosage of IV Insulin in Post-Operative Patients

For post-operative patients requiring IV insulin, the initial recommended dosage is 0.5 U/h, adjusted to maintain blood glucose concentrations between 100-160 mg/dL (5.5-8.9 mmol/L), with transition to subcutaneous insulin once blood glucose levels are stable below 180 mg/dL (10 mmol/L) and oral feeding has resumed. 1, 2

Initial IV Insulin Management

• Start with an initial dose of 0.5 U/h via electronic syringe pump 1
• Titrate the infusion rate to maintain blood glucose in target range:
  • Target range: 100-160 mg/dL (5.5-8.9 mmol/L) 1
  • Avoid tight glycemic control due to hypoglycemia risk
  • Monitor blood glucose hourly during IV insulin administration 2

When to Transition from IV to Subcutaneous Insulin

Transition from IV to subcutaneous insulin when:

• Blood glucose levels are stable for at least 24 hours 3
• Patient has resumed oral feeding 2, 3
• IV insulin infusion rate is <3 U/h (higher rates indicate insulin resistance and increased risk of complications) 2, 3
• Blood glucose levels are <180 mg/dL (10 mmol/L) 2

How to Transition from IV to Subcutaneous Insulin

1. Calculate total daily insulin requirement based on previous 24-hour IV insulin administration 3
2. Convert 50-60% of the 24-hour IV insulin dose to subcutaneous insulin 3
3. Divide the subcutaneous dose:
   • 50% as basal (long-acting) insulin
   • 50% as bolus (rapid-acting) insulin divided between meals 2, 3
4. Administer first dose of long-acting insulin 2-4 hours before stopping IV infusion 3
5. Continue IV insulin for 2-4 hours after first subcutaneous dose to prevent rebound hyperglycemia 3
6. Administer first dose of rapid-acting insulin at the first meal, adjusting for carbohydrate content 2, 3

Special Considerations

For Patients Not Previously on Insulin

• If IV insulin was given for <24 hours and blood glucose remains elevated:
• Start subcutaneous insulin at 0.5-1 IU/kg (half as basal, half as bolus)
• Give only half of the calculated rapid-acting dose if the meal is light 2

For Patients Using Insulin Pumps

• Reconnect personal pump as soon as patient can manage autonomously
• If patient cannot manage pump, initiate basal-bolus subcutaneous regimen 2, 3

For Insulin Resistance

• If IV insulin output is ≥5 IU/h, leave IV insulin in place as this indicates major insulin resistance 2, 3
• If IV insulin output is ≤0.5 IU/h, consider stopping insulin therapy 2

Management of Complications

Hypoglycemia Management

• For blood glucose <3.3 mmol/L (0.6 g/L or 60 mg/dL), administer glucose immediately
• For blood glucose between 3.8-5.5 mmol/L (0.7-1 g/L or 70-100 mg/dL) with symptoms, administer glucose
• Prefer oral glucose for conscious patients; use IV glucose for unconscious patients 2

Hyperglycemia Management

• For blood glucose >16.5 mmol/L (3 g/L or 300 mg/dL) in insulin-treated patients, check for ketosis
• In absence of ketosis, add ultra-rapid insulin analog and ensure hydration
• In presence of ketosis, suspect ketoacidosis, call physician, start ultra-rapid insulin, and consider ICU transfer 2

Monitoring Protocol

• Continue blood glucose monitoring after transition to subcutaneous insulin
• Check blood glucose before meals and at bedtime
• Monitor for at least 48 hours after transition as glycemic control may deteriorate rapidly 3

The evidence clearly shows that proper insulin dosing and careful transition from IV to subcutaneous insulin are critical for preventing complications and optimizing outcomes in post-operative patients.