The Presence of Diabetes and Higher HbA Are Independently Associated With Adverse Outcomes After Surgery.

Objective: Limited studies have examined the association between diabetes and HbA with postoperative outcomes. We investigated the association of diabetes, defined categorically, and the association of HbA as a continuous measure, with postoperative outcomes.

Research Design And Methods: In this prospective, observational study, we measured the HbA of surgical inpatients age ≥54 years at a tertiary hospital between May 2013 and January 2016. Patients were diagnosed with diabetes if they had preexisting diabetes or an HbA ≥6.5% (48 mmol/mol) or with prediabetes if they had an HbA between 5.7 and 6.4% (39 and 48 mmol/mol). Patients with an HbA <5.7% (39 mmol/mol) were categorized as having normoglycemia. Baseline demographic and clinical data were obtained from hospital records, and patients were followed for 6 months. Random-effects logistic and negative binomial regression models were used for analysis, treating surgical units as random effects. We undertook classification and regression tree (CART) analysis to design a 6-month mortality risk model.

Results: Of 7,565 inpatients, 30% had diabetes, and 37% had prediabetes. After adjusting for age, Charlson comorbidity index (excluding diabetes and age), estimated glomerular filtration rate, and length of surgery, diabetes was associated with increased 6-month mortality (adjusted odds ratio [aOR] 1.29 [95% CI 1.05-1.58]; = 0.014), major complications (1.32 [1.14-1.52]; < 0.001), intensive care unit (ICU) admission (1.50 [1.28-1.75]; < 0.001), mechanical ventilation (1.67 [1.32-2.10]; < 0.001), and hospital length of stay (LOS) (adjusted incidence rate ratio [aIRR] 1.08 [95% CI 1.04-1.12]; < 0.001). Each percentage increase in HbA was associated with increased major complications (aOR 1.07 [1.01-1.14]; = 0.030), ICU admission (aOR 1.14 [1.07-1.21]; < 0.001), and hospital LOS (aIRR 1.05 [1.03-1.06]; < 0.001). CART analysis confirmed a higher risk of 6-month mortality with diabetes in conjunction with other risk factors.

Conclusions: Almost one-third of surgical inpatients age ≥54 years had diabetes. Diabetes and higher HbA were independently associated with a higher risk of adverse outcomes after surgery.