Preoperative glucose levels may predict postoperative cardiac outcomes regardless of whether patients have diabetes

For patients without diabetes, predictors of myocardial injury after noncardiac surgery included a casual glucose level of more than 6.86 mmol/L (124 mg/dL) and a fasting glucose level of more than 6.41 mmol/L (116 mg/dL).

Preoperative glucose concentration, particularly casual glucose concentration, may predict risk for postoperative cardiovascular outcomes, especially in patients without diabetes, a study found.

To assess the association between preoperative glucose concentration and postoperative myocardial injury after noncardiac surgery (MINS) and death, researchers applied data from the VISION study, a prospective cohort study done at 12 centers in eight countries. Patients ages 45 years or older who required at least one overnight hospital admission for noncardiac surgery were enrolled from Aug. 6, 2007, to Jan. 11, 2011. Among the 11,954 patients included in this analysis, 2,809 (23%) had diabetes. Results were published July 26 by The Lancet: Diabetes & Endocrinology.

Within the first three postoperative days, 813 patients (7%) developed MINS, while 249 patients (2%) died by day 30. More patients with diabetes had MINS (odds ratio [OR], 1.98 [95% CI, 1.70 to 2.30]; P<0.0001) and died (OR, 1.41 [95% CI, 1.08 to 1.86]; P=0.016) compared with patients without diabetes. Casual glucose concentrations, defined as all glucose concentrations other than fasting, were associated with MINS in all patients (adjusted OR, 1.06 [95% CI, 1.04 to 1.09] per mmol/L of glucose; P=0.0003) and with death in patients without diabetes (adjusted hazard ratio [HR], 1.13 [95% CI, 1.05 to 1.23] per mmol/L; P=0.002).

The researchers observed a progressive relation between unadjusted fasting glucose concentration and MINS (OR, 1.14 [95% CI, 1.08 to 1.20] per mmol/L; P<0.0001), driven by the effect in the subgroup without previous diabetes (P=0.025 for the interaction), as well as a relation with 30-day mortality (HR, 1.10 [95% CI, 1.02 to 1.19] per mmol/L; P=0.013).

For patients without diabetes, predictors of MINS included a casual glucose level of more than 6.86 mmol/L (124 mg/dL) (OR, 1.71 [95% CI, 1.36 to 2.15]; P<0.0001) and a fasting glucose level of more than 6.41 mmol/L (116 mg/dL) (OR, 2.71 [95% CI, 1.85 to 3.98]; P<0.0001). Only a casual glucose concentration more than 7.92 mmol/L (143 mg/dL) predicted MINS in patients with diabetes (OR, 1.47 [95% CI, 1.10 to 1.96]; P=0.0096).

The authors noted that surgeons and cardiologists, internists, and anesthetists who consult on surgical patients can now assess incremental risk using empirically determined glucose thresholds, even after considering all the other known preoperative prognostic factors.

“These results have the potential to enhance conversations about prognosis and decision making before going to surgery,” the authors wrote. “Identification of a better risk marker in people with diabetes could be the subject of future studies. Furthermore, it is not known whether delaying surgery until glucose concentrations are normalised preoperatively would positively or negatively affect outcomes; this is a question that might need to be answered separately for patients undergoing elective and urgent surgery.”