Preoperative HbA1c Optimisation: Annals of Surgery | July 2026

Introduction:

Diabetes is a well-recognised risk factor for postoperative complications, but the optimal level of preoperative glycemic control remains uncertain. This large multi-institutional study evaluated how HbA1c levels influence surgical outcomes and examined the prevalence of previously undiagnosed dysglycemia among surgical patients.

Why was this study needed?

• Diabetes significantly increases perioperative morbidity and mortality.
• The ideal preoperative HbA1c target has remained controversial.
• Many surgical patients have undiagnosed prediabetes or diabetes.
• Previous studies have been small and procedure-specific.
• Better evidence is needed to guide perioperative diabetes optimisation.

Results:

• Nearly one in four surgical patients had previously undiagnosed dysglycemia, with 18% having prediabetes and 5% meeting diagnostic criteria for diabetes, highlighting the importance of routine preoperative HbA1c screening.
• Both very poor glycemic control (HbA1c ≥9%) and near-normal HbA1c in patients with known diabetes were associated with higher postoperative complication rates, suggesting a U-shaped relationship between HbA1c and surgical risk.
• Moderate glycemic control (HbA1c approximately 7–8%) was associated with the most favorable postoperative outcomes, while patients with undiagnosed diabetes experienced higher medical complications and longer hospital stays.

Clinical Impact:

This large ACS-NSQIP analysis supports routine HbA1c screening before major surgery, regardless of a prior diabetes diagnosis. Rather than pursuing aggressive normalization immediately before surgery, clinicians should aim for individualized optimization, avoiding both severe hyperglycemia and excessive glycemic intensification. These findings support a personalized perioperative diabetes management strategy.

Bottom Line:

Preoperative HbA1c matters. Routine HbA1c screening identifies a substantial number of previously undiagnosed patients with dysglycemia, and moderate glycemic control (HbA1c 7–8%) appears to provide the best balance for reducing postoperative complications. Personalized optimization, rather than simply achieving the lowest possible HbA1c, should guide preoperative diabetes management.