How many days pre-operatively should Oral Hypoglycemic Agents (OHAs) be stopped?

Perioperative Management of Oral Hypoglycemic Agents

Direct Recommendation

Most oral hypoglycemic agents (OHAs) should be held on the morning of surgery, with the critical exception of SGLT2 inhibitors, which must be discontinued 3-4 days preoperatively to prevent life-threatening euglycemic diabetic ketoacidosis. 1, 2

Specific Timing by Drug Class

SGLT2 Inhibitors (Highest Priority - Longest Discontinuation)

• Discontinue 3-4 days before surgery for canagliflozin, dapagliflozin, and empagliflozin (≥3 days) and ertugliflozin (≥4 days) 1, 2, 3
• This extended discontinuation period is mandatory because SGLT2 inhibitors create a persistent risk of euglycemic DKA even with normal glucose levels, as their clinical effects continue for 3-4 days after discontinuation 3
• The risk of perioperative DKA is significantly higher in patients taking SGLT2 inhibitors (1.02 vs. 0.69 per 1000 patients) 3
• Critical pitfall: Postoperative ketoacidosis can occur even when patients have withheld SGLT2 inhibitors for >72 hours, so vigilance is required 3

Metformin

• Hold on the day of surgery only 1, 2
• While older concerns about lactic acidosis led to more conservative approaches, current guidelines support holding metformin only on the operative day 4
• This represents a less restrictive approach than historically practiced

All Other Oral Hypoglycemic Agents

• Hold on the morning of surgery 1, 2
• This includes sulfonylureas, DPP-4 inhibitors, thiazolidinediones, and meglitinides
• The primary concern is hypoglycemia during perioperative fasting 4

Evidence Quality and Nuances

The strongest evidence comes from the American Diabetes Association 2021 guidelines, which provide explicit timing recommendations 1. These are reinforced by the 2025 Praxis Medical Insights synthesis of multiple guideline sources 2, 3. The SGLT2 inhibitor recommendations are particularly well-supported given the serious risk of euglycemic DKA, which presents with metabolic acidosis (pH <7.3) despite blood glucose <250 mg/dL 3.

One notable contradiction exists: UK guidelines suggest a less conservative approach for SGLT2 inhibitors, recommending omission only the day before and day of the procedure 3. However, given the severity of euglycemic DKA and the American guidelines' more cautious stance, the 3-4 day discontinuation period should be followed in clinical practice.

Perioperative Monitoring Requirements

• Monitor blood glucose at least every 2-4 hours while the patient is NPO 1, 2
• Target blood glucose range: 100-180 mg/dL perioperatively 2
• Dose with short- or rapid-acting insulin as needed to maintain target range 1, 2

Special Considerations for SGLT2 Inhibitors

Heart Failure Patients

• Cessation of SGLT2 inhibitors may worsen heart failure, creating a clinical dilemma that requires careful risk-benefit assessment 3
• The cardiovascular benefits must be weighed against DKA risk

Prevention Strategies During Discontinuation

• Maintain adequate hydration 3
• Avoid prolonged fasting periods 3
• Consider glucose-containing IV fluids if prolonged fasting is unavoidable 3
• Monitor both glucose and ketone levels 3

Resumption Criteria

• Do not restart SGLT2 inhibitors until the patient is clinically stable and has resumed a normal diet 3
• Typically 24-48 hours after surgery 3
• Ensure capillary ketones are <0.6 mmol/L before restarting 3

Common Pitfalls to Avoid

• Failing to discontinue SGLT2 inhibitors 3-4 days preoperatively leads to risk of euglycemic DKA, which can be life-threatening 2, 3
• Continuing sulfonylureas on the day of surgery increases hypoglycemia risk during fasting 4
• Inadequate glucose monitoring during the perioperative period results in undetected hypo- or hyperglycemia 2
• Restarting SGLT2 inhibitors too early postoperatively before adequate oral intake is established 3