Treatment of Severe Hyperglycemia in Patients Without Diabetes After Colorectal Surgery

Several studies have suggested that intravenous insulin therapy for post-operative hyperglycemia improves outcomes after colorectal surgery. Despite the potential benefit, there is a reluctance to use this approach in patients without diabetes mellitus because of an unproven benefit and the potential for hypoglycemia. In this study, we examined whether sliding-scale insulin is sufficient to improve outcomes or if stricter glucose control is necessary. Of 1,064 consecutive colorectal surgery patients between August 2016 and December 2021, 478 patients without diabetes mellitus had an average of 6.4 ± 3.1 glucose samples taken within 48 hours after surgery. Sixty-six percent of patients with severe hyperglycemia (glucose ≥180 mg/dL) received sliding-scale insulin. Complication rates and effects of insulin were examined. Severe hyperglycemia was associated with a higher total infection rate (p < 0.002), National Healthcare Safety Network-reported infections (NHSN; p < 0.026), total complications (p < 0.001), and length of stay (LOS; p < 0.000). Sliding-scale insulin did not lower the risk of infection or other complications. Hypoglycemia (glucose <70 mg/dL) occurred in 3.5% of patients, but was not related to insulin use, and was predictable with clinical variables: albumin (p < 0.032), operative duration (p < 0.012), and average post-operative glucose (p < 0.002; area under the curve [AUC], 0.86). Our data confirm that severe post-operative hyperglycemia in patients without diabetes mellitus after colorectal surgery is associated with complications. Sliding-scale insulin was safe but not effective. Treatment before severe hyperglycemia is reached, not after its occurrence, may be beneficial.