This study investigates the relationship between diabetes mellitus (DM), glycated haemoglobin (HbA1c), and postoperative outcomes among patients undergoing hip and knee arthroplasty.
We conducted a single-centre cohort study of patients who underwent primary hip or knee arthroplasty between June 2008 and December 2019 and for whom preoperative HbA1c had been recorded. Cases were categorized by preoperative HbA1c as ‘diabetes’ (≥ 48 mmol/mol), ‘prediabetes’ (≥ 42 mmol/mol and < 48 mmol/mol), 'no diabetes' (< 42 mmol/mol), or in 'remission' (preoperative HbA1c < 42 mmol/mol but having a historic HbA1c result ≥ 42 mmol/mol). Multivariable logistic regression and restricted cubic splines were used to examine the association between diabetes status, HbA1c, and early postoperative outcomes.
Analysis of 9,454 procedures (18.4% diabetes, 23.5% prediabetes, 49.7% no diabetes, 8.4% in remission) revealed that DM was associated with a 50% greater likelihood of experiencing one or more postoperative complications (odds ratio (OR) 1.47 (95% CI 1.26 to 1.71)), a 60% greater risk of acute kidney injury or electrolyte abnormality (OR 1.57 (95% CI 1.33 to 1.87)), and more than double the risk of postoperative urinary tract infection (OR 2.25 (95% CI 1.15 to 4.52)) and deep surgical site infection (OR 2.03 (95% CI 1.05 to 3.86)) compared to individuals without diabetes. There was a substantial increase in complication risk as HbA1c entered prediabetes range with no evidence of a plateau or threshold effect, and a profound reduction in the risk of almost all recorded complications for patients in remission from previously elevated HbA1c.
DM was associated with an increased risk of almost all measured early postoperative complications. Interventions to reduce elevated HbA1c, to any degree, may benefit patient outcomes, however these must be balanced with the risk of iatrogenic harm.

© 2025 Holleyman et al.