Assess for a relationship between immediate preoperative glucose concentrations and postoperative complications.

Retrospective cohort study.

Single large, tertiary care academic medical center.

A five-year registry of all patients at our hospital who had a glucose concentration (plasma, serum, or venous/capillary/arterial whole blood) measured up to 6 h prior to a non-emergent surgery.

The glucose registry was cross-referenced with a database from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). We applied an outcomes review to the subset of patients for whom we had data from both registries (n = 1774).

Preoperative glucose concentration in the full population as well as the subgroups of patients with or without diabetes were correlated with adverse postsurgical outcomes using 1) univariable analysis and 2) full multivariable analysis correcting for 27 clinical factors available from the ACS NSQIP database. Logistic regression analysis was performed using glucose level either as a continuous variable or as a categorical variable according to the following classifications: mild (≥140 mg/dL; ≥7.8 mmol/L), moderate (≥180 mg/dL; ≥10 mmol/L), or severe (≥250 mg/dL; ≥13.9 mmol/L) hyperglycemia. A third analysis was performed correcting for 7 clinically important factors (age, BMI, predicted duration of procedure, sex, CKD stage, hypoalbuminemia, and diabetic status) identified by anesthesiologists and surgeons as immediately available and important for decision making.

Univariable analysis of all patients and the subgroups of patients without diabetes or with diabetes showed that immediate preoperative mild or moderate hyperglycemia correlates with postoperative complications. Statistical significance was lost in most groups using full multivariable analysis, but not when correcting for the 7 factors available immediately preoperatively. However, for all patients with diabetes, moderate hyperglycemia (≥180 mg/dL; ≥10 mmol/L) continued to significantly correlate with complications even in the full multivariable analysis [odds ratio (OR) 1.79; 95% Confidence Intervals (CI) 1.10, 2.92], and with readmission/reoperation within 30 days [OR 1.93; 95% CI 1.18, 3.13].

Preoperative hyperglycemia within 6 h of surgery is a marker of adverse postoperative outcomes. Among patients with diabetes in our study, a preoperative glucose level ≥ 180 mg/dL (≥10 mmol/L) independently correlates with risk of postoperative complications and readmission/reoperation. These results should encourage future work to determine whether addressing immediate preoperative hyperglycemia can improve complication rates, or simply serves as a marker of higher risk.