What are the guidelines for in-hospital treatment of diabetes in patients undergoing surgery?

In-Hospital Diabetes Management with Surgery

For surgical patients with diabetes, maintain perioperative blood glucose between 100-180 mg/dL, discontinue SGLT2 inhibitors 3-4 days before surgery, hold metformin and other oral agents on the day of surgery, reduce basal insulin by 25% the evening before surgery, and use basal-bolus insulin regimens rather than correction-only insulin to reduce perioperative complications and mortality. 1

Preoperative Optimization

A1C Targets

• Target A1C <8% for elective surgeries to reduce surgical risk, mortality, and infection rates 1
• Some institutions have developed A1C optimization programs prior to elective procedures 1

Medication Management Before Surgery

SGLT2 Inhibitors (Critical):

• Discontinue 3-4 days before surgery to prevent life-threatening euglycemic diabetic ketoacidosis, which can occur even with normal glucose levels 1, 2
• This is the most critical medication adjustment, as ketoacidosis can develop even when glucose appears normal 2
• Do not restart until patient is clinically stable, resumed normal diet (typically 24-48 hours post-surgery), and capillary ketones are <0.6 mmol/L 2

Metformin:

• Hold only on the day of surgery 1, 2
• Current guidelines support this less restrictive approach compared to historical practice 2

All Other Oral Hypoglycemic Agents:

• Hold on the morning of surgery (sulfonylureas, DPP-4 inhibitors, thiazolidinediones, meglitinides) 1, 2

GLP-1 Receptor Agonists:

• Limited data exist on perioperative use and effects on delayed gastric emptying 1
• Exercise caution with timing

Insulin Adjustments Evening Before Surgery

Reduce basal insulin by 25% the evening before surgery - this approach achieves better perioperative glucose control with lower hypoglycemia risk compared to usual dosing 1, 3

Morning of Surgery Insulin Dosing:

• NPH insulin: Give one-half of usual dose 1
• Long-acting basal insulin analogs: Give 75-80% of usual dose 1
• Insulin pumps: Adjust basal rates based on diabetes type and clinical judgment 1

Intraoperative Management

Blood Glucose Targets

• Maintain glucose 100-180 mg/dL within 4 hours of surgery 1, 3
• Do not pursue stricter targets (<80-180 mg/dL) - they do not improve outcomes and significantly increase hypoglycemia risk 1, 3
• Continuous glucose monitoring (CGM) should not be used alone during surgery 1

Monitoring and Insulin Administration

• Monitor blood glucose at least every 2-4 hours while patient is NPO 1, 3
• Administer short- or rapid-acting insulin as needed to maintain target range 1, 3
• For critically ill patients, continuous intravenous insulin is standard of care 1, 3

Postoperative Management

Insulin Regimen Selection

Use basal-bolus insulin regimens (basal insulin plus premeal short/rapid-acting insulin) rather than correction-only insulin in noncardiac general surgery patients - this approach improves glycemic outcomes and reduces perioperative complications 1, 3

This represents a critical practice point: correction-only ("sliding scale") insulin without basal coverage is associated with worse outcomes 1, 3

Continued Glucose Targets

• Maintain 100-180 mg/dL in the postoperative period 3
• Continue monitoring every 2-4 hours while NPO 1, 3

Special Situations

Glucocorticoid-Induced Hyperglycemia

• Glucocorticoids induce hyperglycemia in 56-86% of hospitalized patients, increasing mortality and morbidity risk (infections, cardiovascular events) 1
• Morning prednisone/prednisolone causes disproportionate afternoon and evening hyperglycemia 1
• Require substantial increases in prandial and correction insulin (40-60% or more) in addition to basal insulin 1
• Daily adjustments based on glycemia levels and anticipated changes in glucocorticoid type, dosage, and duration are critical 1

Diabetic Ketoacidosis (DKA) and Hyperglycemic Hyperosmolar State (HHS)

• Continuous intravenous insulin is standard of care for critically ill patients 1
• Administer basal insulin 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia and recurrent ketoacidosis 1
• Low-dose basal insulin analog given concurrently with IV insulin infusion may prevent rebound hyperglycemia without increasing hypoglycemia risk 1
• Treat underlying causes (sepsis, myocardial infarction, stroke) 1

Critical Pitfalls to Avoid

• Never pursue glucose targets <100 mg/dL perioperatively - increases hypoglycemia without benefit 3
• Never use correction-only insulin without basal insulin in general surgery patients 1, 3
• Never continue SGLT2 inhibitors within 3-4 days of surgery - risk of euglycemic DKA 2
• Never stop IV insulin without prior subcutaneous basal insulin administration - causes rebound hyperglycemia 1
• Never fail to adjust insulin for glucocorticoid therapy - leads to severe hyperglycemia and complications 1