What are the fasting and postprandial glucose targets for a 65-year-old Indian woman undergoing total knee replacement surgery?

Perioperative Glucose Targets for Total Knee Replacement

For a 65-year-old Indian woman undergoing total knee replacement surgery, maintain fasting and postprandial glucose between 100–180 mg/dL (5.6–10.0 mmol/L) throughout the entire perioperative period. 1, 2

Specific Glucose Targets

Fasting Glucose Target

• 100–180 mg/dL (5.6–10.0 mmol/L) starting from the preoperative period and continuing through surgery 1, 2
• This target should be achieved within 4 hours before the surgical incision 1, 2
• Avoid tighter targets (<100 mg/dL) as they significantly increase hypoglycemia risk without improving surgical outcomes 1, 2, 3

Postprandial Glucose Target

• 100–180 mg/dL (5.6–10.0 mmol/L) after meals in the postoperative period 1, 2
• The same range applies throughout—there is no separate postprandial target 1, 2

Critical Preoperative Considerations

HbA1c Assessment

• Target HbA1c <8% for elective total knee replacement to reduce surgical risk, mortality, and infection rates 1, 2, 3
• If HbA1c >8%, consider delaying surgery for glycemic optimization when feasible 2, 4

Surgical Scheduling

• Schedule as the first case of the morning to minimize fasting duration and reduce glycemic disruption 1, 2, 4

Monitoring Requirements

Frequency

• Check blood glucose every 1–2 hours during surgery 1
• Monitor at least every 2–4 hours while NPO in the pre- and postoperative periods 1, 2, 3

Method

• Use venous or arterial blood samples rather than capillary finger-stick measurements, as capillary readings overestimate glucose levels, especially during vasoconstriction 1
• A capillary reading of ≤70 mg/dL (3.8 mmol/L) should be treated as hypoglycemia and requires immediate laboratory confirmation 1

Medication Management

Preoperative Adjustments

• Hold metformin on the day of surgery 1, 2, 3
• Discontinue SGLT2 inhibitors 3–4 days before surgery to prevent euglycemic diabetic ketoacidosis 1, 2, 3
• Hold all other oral glucose-lowering agents the morning of surgery 1, 2

Insulin Dosing

• Administer 75–80% of usual long-acting basal insulin analog dose (glargine, detemir, degludec) on the morning of surgery 1, 2
• Alternatively, give 50% of usual NPH insulin dose if that is the patient's basal insulin 1, 2
• Reducing the evening pre-surgery insulin dose by 25% improves perioperative glucose control with lower hypoglycemia risk 2, 3

Intraoperative Management

Insulin Administration

• Use continuous intravenous insulin infusion if the patient requires insulin during surgery, as this provides more predictable absorption and allows rapid titration 1, 5
• Maintain the 0.90–1.80 g/L (5.0–10.0 mmol/L) target throughout the procedure 1
• Always administer IV insulin with concurrent IV glucose (equivalent of 4 g/hour) and monitor potassium every 4 hours to prevent insulin-induced hypokalemia 1

Postoperative Management

Insulin Regimen

• Use basal-bolus insulin regimens (basal insulin plus premeal rapid-acting insulin) rather than correction-only sliding scale insulin, as this approach significantly improves glycemic outcomes and reduces complications in orthopedic surgery patients 2, 3, 6
• Continue targeting 100–180 mg/dL in the postoperative period 1, 2, 3

Transition from IV to Subcutaneous Insulin

• Administer subcutaneous basal insulin 2–4 hours before stopping IV insulin to prevent rebound hyperglycemia 1, 3
• Resume oral feeding as soon as possible and restart home diabetes medications with the first meal 1, 4

Special Considerations for This Patient Population

Infection Risk in Total Knee Replacement

• Postoperative hyperglycemia >180 mg/dL is an independent risk factor for periprosthetic joint infection in total joint replacement patients 7
• The standardized subcutaneous insulin protocol targeting 100–180 mg/dL has been shown to be both safe and effective in preventing infections in total joint replacement patients 7
• Revision surgery, female-to-male comparison (males at higher risk), and obesity are independent factors causing significant glycemic elevation in total joint replacement patients 7

Monitoring for Hyperglycemia

• Start evaluating for hyperglycemia in the post-anesthesia care unit immediately after surgery 7
• Initiate insulin protocol when fasting glucose >140 mg/dL or postprandial glucose >180 mg/dL 7
• Discontinue insulin when blood glucose decreases to <100 mg/dL 7

Critical Pitfalls to Avoid

• Never pursue glucose targets <100 mg/dL perioperatively, as this increases hypoglycemia risk without mortality or morbidity benefit 1, 2, 3
• Never use correction-only ("sliding scale") insulin without basal insulin coverage in orthopedic surgery patients, as this is associated with worse outcomes and higher complication rates 2, 3, 6
• Never continue SGLT2 inhibitors within 3–4 days of surgery, as this poses significant risk of euglycemic diabetic ketoacidosis 1, 2, 3
• Never stop IV insulin without prior subcutaneous basal insulin administration, as this causes dangerous rebound hyperglycemia 1, 3
• Do not postpone surgery for glucose <297 mg/dL (16.5 mmol/L) unless ketosis is present; treat with corrective insulin and proceed 4

Evidence Strength

The 100–180 mg/dL target represents the strongest current evidence from the American Diabetes Association 2025 guidelines 1 and is reinforced by multiple high-quality guidelines 1, 2, 3. This moderate glycemic control target (versus strict targets of 80–110 mg/dL) provides the optimal balance between reducing hyperglycemia-related complications and avoiding dangerous hypoglycemia 1, 8. Meta-analysis data confirm that moderate targets (150–200 mg/dL) reduce postoperative mortality and stroke compared with liberal targets (>200 mg/dL), while stricter targets provide no additional benefit 8.