Elevated preoperative HA1C is associated with increased perioperative risk

The role of HA1C

HA1C provides insight into glucose control over the preceding 3–4 months. Elevated preoperative HA1C is associated with increased perioperative risk and holds promise as a preoperative screening modality.34,35 Gustafsson and colleagues,35 in a prospective study of 120 patients without known DM having major colorectal surgery, were able to show patients with preoperative HA1C > 6% were at significantly greater risk for pneumonia, urinary tract infection, pleural effusions, and postoperative ileus, and had significantly elevated postoperative glucose levels in this group of patients. Others retrospectively linked preoperative HA1C to postoperative complications. Dronge and colleagues36 showed that preoperative HA1C<7% is significantly associated with decreased infectious complications including pneumonia, wound infection, urinary tract infection, and sepsis. Hudson and colleagues37 demonstrated a preoperative HA1C > 6% in non-diabetics is independently associated with greater early mortality after elective cardiac surgery.

Elevated HA1C, as a marker of poor glycaemic control, correlates with increased perioperative risk in diabetic patients. Han and Kang38 demonstrated a significant increase in wound complications after total knee arthroplasty in diabetic patients with HA1C >8%. Diabetic patients with an HA1C >6.5% have an increased risk of pneumonia, urinary tract infection, and superficial wound infections after elective cardiac surgery when compared with diabetics with HA1C <6.5%.34 Currently, the ADA suggests that practitioners consider obtaining an HA1C on diabetic patients admitted to the hospital if the result of testing in the previous 2–3 months is not available. The ADA also suggests HA1C testing in patients with risk factors for undiagnosed DM who exhibit hyperglycaemia in the hospital.29

Although elevated HA1C is associated with adverse outcomes, there is a lack of data to show delaying elective surgery to correct HA1C is beneficial. Nonetheless, HA1C screening does allow identification of unrecognized DM and stratification of perioperative risk. Aggressive approaches to lowering HA1C in non-surgical patients have not been shown to decrease mortality.39 Future investigations will likely clarify the role of preoperative HA1C management on modifying surgical outcome.

Clinicians should be reminded that the accuracy of HA1C can vary by measurement technique. Erroneous results are possible in patients with haemoglobinopathies, chronic bleeding, iron deficiency, renal failure-induced anaemia, recent transfusions, or ongoing haemolysis.40