Is an Hemoglobin A1c (HbA1c) level of 8% acceptable for preoperative (preop) purposes?

Is A1c of 8% Acceptable for Preoperative Purposes?

An A1c of 8% is NOT acceptable for elective surgery and requires preoperative diabetology consultation and treatment intensification to reduce surgical complications. 1

Guideline-Based Thresholds

The French Society of Anaesthesia and Intensive Care Medicine explicitly identifies HbA1c >8% as representing preoperative glycemic imbalance that mandates referral to a diabetologist before proceeding with elective surgery. 1 This threshold is consistent across multiple guideline bodies:

• The American Diabetes Association recommends targeting A1C <8% for elective surgeries to reduce surgical risk, mortality, and infection rates. 2
• For cardiac surgery specifically, optimal preoperative glycemic control is defined as HbA1c <6.5%, with evidence-based recommendations suggesting intervention to achieve HbA1c <7%. 1

Clinical Evidence Supporting This Threshold

The concern about A1c ≥8% is supported by substantial surgical outcome data:

• In diabetic patients undergoing infrainguinal lower extremity bypass, HbA1c ≥8% was independently associated with a 37% increased risk of major adverse limb events (OR 1.37,95% CI 1.01-1.86) compared to HbA1c 6-7%. 3
• In total knee arthroplasty patients, preoperative HbA1c ≥8% increased the risk of wound complications six-fold (OR 6.07,95% CI 1.12-33.0). 4
• In spinal instrumentation surgery, patients with HbA1c ≥7% had a 35.3% surgical site infection rate versus 0% in those with HbA1c <7%. 5

When Surgery Cannot Be Delayed

If surgery is urgent or emergent and cannot be delayed for glycemic optimization:

• Proceed with surgery but implement aggressive perioperative glucose monitoring (every 2-4 hours while NPO) and maintain glucose 100-180 mg/dL. 2
• Use basal-bolus insulin regimens postoperatively rather than correction-only insulin, as this improves outcomes and reduces complications. 2
• Recognize that postoperative glucose control matters more than preoperative A1c for 30-day mortality when both are measured—A1c loses its predictive value when controlling for perioperative glucose levels. 6

Critical Action Steps for A1c = 8%

For elective surgery with A1c of 8%:

1. Refer to diabetology/endocrinology for treatment intensification before proceeding. 1
2. Delay elective surgery until A1c improves to <8% (ideally <7%). 1, 2
3. Measure preoperative A1c for risk stratification in all diabetic patients. 1
4. Discontinue SGLT2 inhibitors 3-4 days before surgery to prevent euglycemic diabetic ketoacidosis. 2

Important Nuance

While elevated A1c predicts poor outcomes, the association between preoperative A1c and readmissions disappears when controlling for postoperative glucose management. 7 This suggests that patients with higher A1c receive more intensive perioperative monitoring and treatment, which may mitigate some risk. However, this does NOT justify accepting A1c of 8% for elective cases—it reinforces that these patients require enhanced perioperative protocols that are best implemented after preoperative optimization. 7