How should glipizide be discontinued and glucose monitored in a type 2 diabetic patient undergoing surgery to prevent peri‑operative hypoglycaemia?

Perioperative Management of Glipizide

Hold glipizide on the morning of surgery and monitor blood glucose every 2-4 hours while NPO, maintaining a target range of 100-180 mg/dL with short-acting insulin as needed. 1, 2

Timing of Discontinuation

• Withhold glipizide on the morning of surgery only—unlike SGLT2 inhibitors which require 3-4 days of preoperative discontinuation, sulfonylureas like glipizide need only be held the day of the procedure. 1, 2

• The evening dose before surgery may be taken as usual if the patient is eating normally. 3

• For ambulatory procedures where the patient will miss only a single meal and resume eating within 2-3 hours, some protocols allow continuation of oral agents, though this carries higher hypoglycemia risk with sulfonylureas. 4

Rationale for Discontinuation

The primary concern with glipizide perioperatively is prolonged and severe hypoglycemia due to:

• Stimulation of insulin secretion independent of glucose levels, which persists even during fasting states when surgical stress would otherwise elevate glucose. 5, 6

• Elimination half-life of 2-7 hours with duration of action extending beyond this, creating risk during the NPO period. 6

• Increased susceptibility in elderly patients (the typical surgical population), who have impaired recognition of hypoglycemic symptoms and often have renal impairment that prolongs drug action. 5, 7

• Severe hypoglycemia can be prolonged or recurrent for up to 60 hours after glipizide administration, particularly in patients with renal dysfunction or those on multiple medications. 7

Perioperative Glucose Monitoring

• Check capillary blood glucose at least every 2-4 hours while the patient is NPO. 1, 2, 4

• Target blood glucose range is 100-180 mg/dL (5.6-10.0 mmol/L) throughout the perioperative period—tighter targets increase hypoglycemia risk without improving outcomes. 1, 2, 3

• If glucose exceeds 180 mg/dL, administer corrective subcutaneous insulin boluses with short- or rapid-acting insulin. 1, 2, 4

Management of Concomitant Insulin Therapy

For patients on both glipizide and basal insulin:

• Give 75-80% of the usual long-acting insulin analog dose (or 50% of NPH dose) on the morning of surgery. 1, 2, 3

• Consider reducing basal insulin by 25% the evening before surgery to improve perioperative glucose control and lower hypoglycemia risk. 3

• Continue to hold glipizide on the morning of surgery even when basal insulin is continued. 1

Postoperative Resumption

• Resume glipizide with the first postoperative meal once the patient is eating normally and blood glucose is in the target range of 90-180 mg/dL. 4

• Continue blood glucose monitoring until the patient is stable on their usual regimen. 4

• If blood glucose exceeds 300 mg/dL (16.5 mmol/L) postoperatively, hospitalization may be required for IV insulin therapy. 4

Critical Risk Factors for Hypoglycemia

Be especially vigilant in patients with:

• Renal impairment (odds ratio 4.0 for severe hypoglycemia)—glipizide metabolites are renally excreted and accumulate with decreased clearance. 5, 7

• Advanced age (mean age 75 years in severe hypoglycemia cases)—elderly patients have impaired counterregulatory responses and difficulty recognizing symptoms. 5, 7

• Polypharmacy—patients experiencing severe hypoglycemia take a median of 5 concomitant drugs versus 2 in controls, particularly diuretics and benzodiazepines which potentiate hypoglycemic effects. 7

• Hepatic insufficiency—diminishes gluconeogenic capacity and may elevate glipizide blood levels. 5

• Malnutrition or prolonged fasting—the surgical NPO period compounds these risks. 5

Common Pitfalls to Avoid

• Do not confuse glipizide management with SGLT2 inhibitor protocols—glipizide requires only day-of-surgery hold, not 3-4 days preoperatively. 1, 2

• Do not continue glipizide "because the patient will only miss one meal"—even a single dose can cause prolonged hypoglycemia lasting up to 60 hours in susceptible patients. 7

• Do not fail to reduce basal insulin doses—continuing full basal insulin doses while holding glipizide still carries hypoglycemia risk during the NPO period. 1, 3

• Do not restart glipizide before the patient is eating normally—premature resumption without adequate carbohydrate intake risks severe hypoglycemia. 4

• Do not rely on patient symptoms to detect hypoglycemia—up to 40% of Type 1 diabetics and 10% of Type 2 diabetics on insulin or sulfonylureas have impaired awareness of hypoglycemia. 1

Scheduling Optimization

• Place diabetic patients first on the morning surgical list to minimize prolonged fasting and reduce glycemic instability. 4, 3

• Early scheduling allows earlier resumption of normal eating and medication schedules, reducing the duration of metabolic disruption. 4