Diabetes, HbA1c Independently Associated With Adverse Postoperative Outcomes

A physician overseeing a patient after surgery
A physician overseeing a patient after surgery
Investigators sought to determine an association between diabetes and HbA1C with postoperative outcomes.

Both diabetes and elevated glycated hemoglobin (HbA1c) show an independent association with increased risk for adverse postoperative outcomes, according to a study recently published in Diabetes Care.

This study was designed to test the hypothesis that diabetes and HbA1c, defined respectively as categorical and continuous variables, are independently associated with adverse postoperative outcomes. The study researchers utilized HbA1c as an indicator of the acuteness of chronic preadmission glycemic status and presence of diabetes.

This observational, prospective study included 7565 patients at least 54 years old, 30% of whom had diabetes and 37% of whom had prediabetes. Researchers measured HbA1c levels of the inpatients from May 2013 to January 2016.

Those with an HbA1c of at least 6.5% (48 mmol/mol) or with preexisting diabetes were diagnosed with diabetes, whereas those with an HbA1c from 5.7 to 6.4% (39 to 48 mmol/mol) were diagnosed with prediabetes. An HbA1c of less than 5.7% (39 mmol/mol) was classified as normal.

The researchers obtained clinical and baseline demographic data and followed up with the participants for a 6-month period, using negative binomial regression and random-effects logistic models to analyze data. A 6-month risk model for mortality was designed via regression tree (CART) analysis and classification.

After adjustments were made for length of surgery, estimated glomerular filtration rate, age, and Charlson comorbidity index with the exception of age and diabetes, diabetes showed a significant association with major complications (adjusted odds ratio [aOR] 1.32; P<.001), increased 6-month mortality (aOR 1.29; P=.014), mechanical ventilation (aOR 1.67; P<.001), length of hospital stay (adjusted incidence rate ratio [aIRR] 1.08; P<.001), and admission to intensive care unit (aOR 1.50; P<.001).

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HbA1c showed an independent association with higher admission to intensive care unit (aOR 1.14; P<.001), major complications (aOR 1.07; P=.03), and length of hospital stay (aIRR 1.05; P<.001). Via CART analysis, the study researchers also reported an increased risk for mortality within 6 months with diabetes in conjunction with separate risks.

Researchers conclude that “[almost] one-third of surgical inpatients age ≥54 years had diabetes. Diabetes and higher HbA1c were independently associated with a higher risk of adverse outcomes after surgery.”


Yong PH, Weinberg L, Torkamani N, et al. The presence of diabetes and higher HbA1c are independently associated with adverse outcomes after surgery [published online March 26, 2018]. Diabetes Care. doi: 10.2337/dc17-2304