Effect of the systemic inflammatory response, as provoked by elective orthopaedic surgery, on HbA1c.

Background In acutely ill patients with new onset hyperglycaemia, plasma glucose cannot reliably distinguish between stress hyperglycaemia and undiagnosed diabetes mellitus. We, therefore, investigated the diagnostic reliability of glycated haemoglobin (HbA1c) in acute illness by prospectively evaluating the effect of the systemic inflammatory response, as provoked by elective orthopaedic surgery, on HbA1c. Methods HbA1c and serum C-reactive protein concentrations were compared before and two days after elective knee or hip surgery in 30 patients without diabetes. C-reactive protein was used to assess the systemic inflammatory response. Results The mean (standard deviation) serum C-reactive protein increased following surgery (4.8 [7.5] vs. 179.7 [61.9] mg/L; P<0.0001). HbA1c was similar before and after surgery (39.2 [5.4] vs. 38.1 [5.1] mmol/moL, respectively; P = 0.4363). Conclusions HbA1c is unaffected within two days of a systemic inflammatory response as provoked by elective orthopaedic surgery. This suggests that HbA1c may be able to differentiate newly presenting type 2 diabetes mellitus from stress hyperglycaemia in acutely ill patients with new onset hyperglycaemia.