Should cataract surgery proceed if a patient didn't hold their SGLT2 (sodium-glucose cotransporter 2) inhibitor?

Perioperative Management of SGLT2 Inhibitors for Cataract Surgery

Cataract surgery should be postponed if a patient has not held their SGLT2 inhibitor as recommended, due to the significant risk of developing perioperative euglycemic diabetic ketoacidosis. 1

Risk Assessment and Rationale

SGLT2 inhibitors significantly increase the risk of perioperative diabetic ketoacidosis (DKA), particularly euglycemic DKA where glucose levels may remain normal despite metabolic derangement:

• The risk of perioperative DKA is 48% higher in patients taking SGLT2 inhibitors compared to those who are not (1.02 vs. 0.69 per 1000 patients) 1
• Euglycemic DKA can occur even in patients without diabetes mellitus 1
• Cases of postoperative euglycemic DKA have been reported even when SGLT2 inhibitors were discontinued 48-72 hours before surgery 2, 3

Recommended Protocol for SGLT2 Inhibitors Before Cataract Surgery

1. Standard recommendation: SGLT2 inhibitors should be omitted the day before and the day of the procedure 1

   • For morning doses: This provides at least a 48-hour gap before a morning procedure
   • For evening doses: This provides at least a 36-hour gap

2. More conservative approach: Discontinue SGLT2 inhibitors 3-4 days before surgery 4

   • This aligns with FDA recommendations and provides greater safety margin 5
   • Particularly important for higher-risk patients

3. Emergency situations: If the patient has taken their SGLT2 inhibitor and requires urgent cataract surgery:

   • Check blood glucose and ketone levels
   • Proceed only if ketones are <0.6 mmol/L and the patient is clinically well 1
   • Implement risk mitigation strategies (see below)

Risk Mitigation Strategies

If surgery must proceed despite inadequate SGLT2 inhibitor hold time:

• Ensure proper hydration and minimize fasting time 1
• Consider glucose-containing IV fluids to prevent ketosis 1
• Monitor glucose and ketone levels before, during, and after surgery 6
• Be vigilant for signs of euglycemic DKA (nausea, vomiting, tachypnea, metabolic acidosis) 3
• Have insulin and dextrose available for immediate treatment if needed 3

Postoperative Management

• Restart SGLT2 inhibitors only when:

  • Patient is eating and drinking normally (usually 24-48 hours after surgery) 1
  • Capillary ketones are <0.6 mmol/L 1
  • No signs of metabolic derangement are present 4

• Provide written sick-day rules to patients at discharge 1

Special Considerations

• Patients on very low-energy/liver reduction diets: SGLT2 inhibitors should be stopped at diet commencement 1
• Patients with heart failure: Weigh the cardiovascular benefits of continuing SGLT2 inhibitors against the risk of ketoacidosis 1
• Emergency surgery carries a higher risk of ketoacidosis (1.1% vs. 0.17% for elective surgery) 1

Key Pitfalls to Avoid

• Relying solely on glucose levels to rule out DKA (euglycemic DKA can occur with normal glucose) 1, 3
• Assuming shorter procedures like cataract surgery are low risk (the stress response and fasting can still trigger ketoacidosis) 6
• Failing to recognize that risk of complications exists on a continuum rather than having a defined threshold 1
• Overlooking that SGLT2 inhibitor pharmacodynamic effects may persist beyond their pharmacokinetic half-life 2

By following these guidelines, clinicians can minimize the risk of perioperative complications while ensuring optimal patient outcomes for cataract surgery.