Clinical Significance of Post-Operative Hyperglycemia in Nondiabetic Patients Undergoing Definitive Surgery for Gastrointestinal Fistula

Background: To evaluate the association between peri-operative hyperglycemia and adverse events in patients with gastrointestinal (GI) fistulas without a pre-operative diagnosis of diabetes mellitus who were undergoing definitive surgery. Methods: Pre-operative and all post-operative blood glucose concentrations (BG) were retrieved for 363 consecutive patients undergoing GI reconstruction from September 2012 to December 2015. Normoglycemic (BG <125 mL/dL), mild hyperglycemia (125-199 mL/dL), and severe hyperglycemia (>= 200 mL/dL) were defined using the highest BG found within the first 48 h post-operatively. Outcomes of interest included 30-d mortality rate and re-operation, time of enteral nutrition resumption, and infectious and non-infectious complications. Results: More than half of the nondiabetic patients (61.4%) experienced hyperglycemia post-operatively. The degree of hyperglycemia correlated with patient age, American Society of Anesthesiologists class, and surgical interventions. Hyperglycemia was associated with re-operation and post-operative complications, the frequency of these complications increasing in parallel with the degree of hyperglycemia. Additionally, post-operative hyperglycemia was associated independently with surgical site infections (p = 0.014), anastomotic leak (p = 0.010), delayed resumption of enteral nutrition (p < 0.001), and longer hospital stay (p < 0.001). Conclusion: Elevated post-operative BG was frequent after surgery in patients with GI fistulas. Post-operative hyperglycemia is significantly associated with unfavorable outcomes, and this risk is related to the degree of BG elevation. Our findings suggest that vigilant post-operative BG monitoring and early appropriate glycemic control are critical for patients, even nondiabetic patients, undergoing definitive surgery for GI fistula.