Elevated preoperative hemoglobin A1C is linked to higher postoperative complications in general surgery.

• 36% of patients had diagnosed diabetes; 6.4% had undiagnosed diabetes with A1C levels indicating the condition.
• Complications risk increased with A1C levels: from 1.06 for <6.0% to 1.32 for >9.0%.
• Undiagnosed diabetes led to 24% higher mortality risk and 11% higher risk of medical complications.

Routine A1C screening can help identify high-risk patients and guide individualized glycemic management, improving surgical outcomes.