How to manage a patient with Type 2 Diabetes Mellitus (T2DM) who is Nil Per Os (NPO) for an operation in the Operating Room (OR)?

Management of Type 2 Diabetes Mellitus Patients Who Are NPO for Surgery

For patients with Type 2 Diabetes Mellitus (T2DM) who will be NPO for surgery, withhold oral hypoglycemic medications on the morning of surgery, administer half of NPH insulin dose or 75-80% of long-acting insulin analog, and monitor blood glucose every 4-6 hours while NPO with correction using short-acting insulin as needed. 1, 2

Preoperative Management

Medication Adjustments

• Oral antidiabetic medications:

  • Withhold all oral hypoglycemic agents on the morning of surgery 1
  • Metformin: Discontinue the evening before surgery 1, 2
  • SGLT2 inhibitors: Discontinue 3-4 days before surgery 2

• Insulin adjustments:

  • Evening before surgery:
    • Continue usual basal insulin dose, or consider reducing by 25% to minimize hypoglycemia risk 2
    • Maintain insulin pump until arrival in surgical unit 1
  • Morning of surgery:
    • NPH insulin: Administer 50% of usual dose 1, 2
    • Long-acting insulin analogs: Administer 60-80% of usual dose 1, 2

Intraoperative Management

Glucose Monitoring

• Monitor blood glucose every 4-6 hours while NPO 1
• Target blood glucose range: 100-180 mg/dL (5.6-10.0 mmol/L) 2
• Use arterial or venous blood samples instead of capillary blood when possible 2

Insulin Administration

• For minor procedures with brief NPO status:
  • Use correction doses of short-acting insulin as needed 1
• For major procedures or prolonged NPO status:
  • Consider basal-bolus insulin regimen rather than sliding scale only 1, 2
  • For significant hyperglycemia (>180 mg/dL), initiate intravenous insulin infusion with glucose (4g/hr) 2

Postoperative Management

Transitioning from IV to Subcutaneous Insulin

When transitioning from IV insulin to subcutaneous insulin:

• Calculate total daily insulin requirement based on IV insulin used in previous 24 hours 1
• Administer half of the 24-hour IV insulin dose as basal insulin 1
• Divide the remaining half into three doses of rapid-acting insulin for meals 1
• Ensure overlap between IV insulin discontinuation and first subcutaneous dose 1

Resuming Oral Medications

• Resume oral medications once patient is eating regularly 1
• Metformin should be restarted only after confirming normal renal function 2

Special Considerations

Hypoglycemia Management

• Treat blood glucose <70 mg/dL (3.9 mmol/L) immediately 1, 2
• For conscious patients: Oral glucose administration 1
• For unconscious patients: IV glucose administration 1
• Continue monitoring after treatment to prevent recurrence 1

Hyperglycemia Management

• For blood glucose >180 mg/dL: Administer correction doses of rapid-acting insulin 1
• For severe hyperglycemia (>300 mg/dL) with ketosis: Consider ICU transfer and IV insulin therapy 1
• Monitor for signs of diabetic ketoacidosis or hyperosmolar states 1

Practical Tips

• Schedule diabetic patients for early morning surgery when possible to minimize fasting time 2
• Basal-bolus insulin regimens show better outcomes than sliding scale alone 1, 2
• Avoid prolonged fasting in diabetic patients 2
• Prevent postoperative nausea and vomiting which can affect glucose control 2

Common Pitfalls to Avoid

• "Hold-the-insulin" routines are dangerous, especially for Type 1 diabetics 3
• Overly tight glycemic control (<80 mg/dL) increases hypoglycemia risk without improving outcomes 2
• Failing to monitor potassium levels when administering insulin 2
• Continuing SGLT2 inhibitors too close to surgery increases diabetic ketoacidosis risk 2

By following this structured approach to managing T2DM patients who are NPO for surgery, you can minimize complications and optimize perioperative glycemic control.