What is the best strategy for managing insulin in the perioperative period for a patient with type 1 diabetes (T1D) on an insulin pump undergoing surgery?

Perioperative Insulin Pump Management in Type 1 Diabetes

Primary Recommendation

For minor elective surgery where only one meal is missed, continue the insulin pump throughout the perioperative period with the patient maintaining their usual basal infusion rate. 1 For major surgery, emergency procedures, abdominal operations, or cases requiring prolonged NPO status (more than one meal), discontinue the pump and transition to intravenous insulin infusion. 1

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Decision Algorithm: Pump Continuation vs. Discontinuation

Continue Pump For:

• Minor elective procedures 1
• Surgery requiring only one missed meal 1
• Procedures where patient will resume eating quickly 1
• Colonoscopy/OGD 1
• Laser surgery 1
• Ultrasound procedures 1

Discontinue Pump For:

• Major surgery 1
• Emergency surgery 1
• Abdominal surgery 1
• Procedures causing significant ileus 1
• NPO status exceeding one meal 1
• Any procedure requiring CT, MRI, or screening radiology 1
• Cardiac catheterization 1
• Pacemaker/AICD placement 1
• Body X-rays (pump must be removed; dental X-rays only require lead apron coverage) 1

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Preoperative Preparation

Patient Discussion and Planning:

• Re-site the infusion set the day before surgery and monitor blood glucose to ensure proper function 1
• Position the infusion site away from the surgical field (e.g., thigh), distant from diathermy use, and accessible to the anesthesiologist 1
• Ensure the patient brings adequate pump supplies for the entire hospital stay 1
• Perform overnight basal assessment before surgery to optimize basal rates 1
• Notify the diabetes pump team to confirm self-management competencies 1
• Schedule patients first on the surgical list to minimize fasting time 1

Equipment Considerations:

• Use plastic (non-metal) infusion sets to avoid interference with surgical equipment 1
• Do not rely on continuous glucose monitors (CGM) during surgery due to discrepancies between interstitial and capillary glucose, which are exaggerated by hemodynamic changes and altered subcutaneous perfusion 1

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Intraoperative Management

If Continuing Pump:

• Maintain the usual basal infusion rate throughout surgery 1
• Some protocols recommend reducing to 80% of basal rate during surgery, though this is based on the assumption of supraphysiological baseline rates 1
• Monitor capillary blood glucose hourly 1
• Target glucose range: 6-10 mmol/L (acceptable range 4-12 mmol/L) 1
• Site the pump as far from electrocautery use as possible, though pump malfunction from electrocautery has not been documented 1

If Discontinuing Pump:

• Start IV insulin infusion at least 30 minutes before disconnecting the pump to prevent rapid hyperglycemia and ketosis 1
• Use the patient's programmed basal rate as a guide for IV insulin requirements (equivalent subcutaneous and IV rates) 1
• In emergency situations where 30-minute overlap is impossible, commence IV insulin immediately without delay 1
• Monitor blood glucose hourly via capillary, venous, or arterial sampling 1

Troubleshooting During Surgery:

• If blood glucose becomes uncontrolled perioperatively, switch to IV insulin infusion 1
• If blood glucose falls below 4 mmol/L (72 mg/dL), treat hypoglycemia per local protocol 1
• If hypoglycemia is recurrent, disconnect the pump and commence IV insulin infusion 1

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Postoperative Management

If Pump Was Continued:

• Continue hourly capillary blood glucose monitoring until the patient is fully conscious and capable of managing their pump 1
• Once alert, the patient can use the pump's built-in bolus calculator to determine correction doses for elevated glucose 1
• Resume bolus insulin dosing with the first postoperative carbohydrate ingestion 1
• Continue increased monitoring frequency for 1-2 days after surgery to re-establish baseline status 1

If Pump Was Discontinued:

• When restarting the pump, run IV insulin alongside subcutaneous infusion for 2 hours with hourly glucose monitoring to establish a subcutaneous depot before discontinuing IV insulin 1
• This overlap prevents dangerous gaps in insulin coverage 1

Managing Postoperative Hyperglycemia:

• Minor glucose elevations can be monitored and corrected with the next meal bolus 1
• Significant hyperglycemia may indicate pump failure, accidental disconnection, or physiological stress response 1
• Patients familiar with "sick day rules" can apply these algorithms postoperatively 1

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Critical Pitfalls to Avoid

• Never expose insulin pumps to ionizing radiation or electromagnetic fields during CT, MRI, or screening procedures 1
• Do not use CGM values for intraoperative glucose monitoring—rely exclusively on capillary or blood glucose measurements 1
• Avoid abrupt pump discontinuation without IV insulin overlap, as type 1 diabetes patients develop rapid hyperglycemia and ketosis within hours 1
• Do not assume pump continuation is safe for all procedures—major surgery, abdominal operations, and prolonged NPO status require IV insulin 1
• Ensure adequate tissue perfusion and blood pressure maintenance during surgery, as pump function depends on subcutaneous perfusion 1

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Evidence Quality Note

The British Journal of Anaesthesia guidelines 1 represent the highest quality evidence available for this specific population, providing comprehensive algorithmic recommendations. While some evidence suggests beneficial effects of continuing pump therapy during elective surgery (lower fasting glucose, more stable control), these studies had ambiguous trial designs and lack confirmation 1. Importantly, no evidence demonstrates detrimental effects of continuing basal insulin infusion during appropriate surgical procedures 1.