How soon before surgery should glipizide (a sulfonylurea) be discontinued to minimize the risk of hypoglycemia?

Perioperative Management of Glipizide

Glipizide, as a sulfonylurea oral hypoglycemic agent, should be held on the morning of surgery only—not discontinued days in advance.

Evidence-Based Timing

The most recent and authoritative guidelines from the American Diabetes Association (2024) provide clear direction for perioperative management of oral glucose-lowering agents 1:

• Hold glipizide and other oral glucose-lowering agents (excluding SGLT2 inhibitors and metformin) on the morning of surgery or procedure 1
• Metformin should be held on the day of surgery only 1
• SGLT2 inhibitors require a much longer discontinuation period of 3-4 days before surgery to prevent euglycemic diabetic ketoacidosis 1, 2

Rationale for Morning-of-Surgery Discontinuation

The primary concern with sulfonylureas like glipizide is hypoglycemia risk during the perioperative fasting period, not prolonged drug effects requiring days of discontinuation 1:

• Sulfonylureas stimulate insulin secretion regardless of glucose levels, creating hypoglycemia risk when patients are NPO 3
• Holding the medication on the morning of surgery provides adequate protection against intraoperative hypoglycemia while avoiding prolonged preoperative hyperglycemia 4
• One randomized controlled trial actually demonstrated that continuing oral hypoglycemics preoperatively resulted in better glycemic control (mean 138 vs 156 mg/dL, P<.001) without increased hypoglycemia in ambulatory surgery patients 4

Perioperative Glycemic Management

Once glipizide is held on the morning of surgery 1:

• Monitor blood glucose at least every 2-4 hours while the patient is NPO 1
• Target perioperative blood glucose of 100-180 mg/dL 1
• Dose with short- or rapid-acting insulin as needed to maintain target range 1
• Basal insulin dosing should be reduced: give one-half of NPH dose or 75-80% of long-acting analog insulin 1
• Reducing basal insulin by 25% the evening before surgery further decreases hypoglycemia risk while maintaining glycemic targets 1

Critical Distinction from Other Diabetes Medications

Do not confuse glipizide management with SGLT2 inhibitors, which have entirely different perioperative requirements 2:

• SGLT2 inhibitors (canagliflozin, dapagliflozin, empagliflozin) must be stopped 3-4 days preoperatively due to risk of euglycemic diabetic ketoacidosis 1, 2
• This ketoacidosis can occur even with normal glucose levels and even when held for >72 hours 2
• Metformin requires only day-of-surgery discontinuation 1

Common Pitfalls to Avoid

• Do not discontinue glipizide days in advance—this creates unnecessary preoperative hyperglycemia without added safety benefit 4
• Do not use correction-dose insulin alone without basal insulin coverage, as basal-bolus regimens have superior outcomes and lower complication rates in noncardiac surgery 1
• Do not target glucose <100 mg/dL perioperatively, as stricter targets increase hypoglycemia without improving outcomes 1
• Ensure glucose monitoring continues every 2-4 hours during the NPO period, as 84% of severe hypoglycemic episodes are preceded by earlier mild hypoglycemia 1