The impact of preoperative testing for blood glucose concentration and haemoglobin A1c on mortality, changes in management and complications in noncardiac elective surgery: a systematic review.

Background: The risks associated with surgery are elevated in patients with diabetes mellitus. For this reason, preoperative diagnostics frequently include the measurement of blood glucose and haemoglobin A1c (HbA1c), but it is unclear whether these tests contribute to improved perioperative or postoperative outcomes.

Objectives: This systematic review aimed to evaluate the evidence that preoperative testing for blood glucose and HbA1c might influence the following outcome parameters: changes in clinical management; mortality; and the incidence of perioperative and postoperative complications in patients undergoing elective, noncardiac surgery.

Design: We performed a systematic search of the literature from January 2001 to March 2013, thus updating a review carried out by the National Institute for Health and Clinical Excellence (NICE) up to the year 2001.

Eligibility Criteria: Controlled studies including cohort and case-control studies with a population of at least 60 patients were eligible.

Results: The search retrieved 1346 records (including hand-search). Twenty-two studies met all inclusion criteria and were included in the review. Fifteen cohort and two case-control studies evaluated the effectiveness of preoperative blood glucose testing and nine studies the effectiveness of testing HbA1c. Four of the included studies evaluated both tests. There were no data derived from high-quality studies supporting routine preoperative testing for blood glucose or HbA1c in otherwise healthy adult patients undergoing elective noncardiac surgery. Only in vascular and orthopaedic surgery may screening identify patients at an increased risk.

Conclusion: Preoperative blood glucose testing and testing for HbA1c is not required in nondiabetic patients unless there are clinical sings arousing suspicion. Patients scheduled for vascular and orthopaedic surgery carry an elevated risk justifying preoperative testing for blood glucose or HbA1c as a screening tool.