Pre-operative glucose as a screening tool in patients without diabetes

Background: Although hyperglycemia has been associated with poor post-operative outcomes, pre-operative hyperglycemia is not used as a screening tool in patients without diabetes. We evaluated pre-operative glucose as a marker for post-operative outcomes in patients without diabetes in order to assess its usefulness as a potential screening tool. Materials and methods: Clinical characteristics for a sample of 6,683 patients without diabetes who underwent non-emergent vascular and general surgery were collected from the American College of Surgeons National Surgical Quality Improvement Program, Brigham and Women’s Hospital database. Last glucose measured within 30 days prior to surgery was the main predictor variable with post-operative infection within 30 days as the primary outcome. Results: For patients without known diabetes with pre-operative glucose of 100-139 mg/dL and 140-179 mg/dL, post-operative infection rates were significantly higher (9.33% and10.16%, respectively) than that of patients with pre-operative glucose of 70-99 mg/dL (5.62%, P<0.001). The risk-adjusted odds of post-operative infection increased by 40% (95% CI, 13%-72%) for each 40 mg/dL increase in pre-operative glucose over the range 70-179 mg/dL. Follow-up data demonstrated that 15% of patients with pre-operative glucose ≥100 mg/dL were diagnosed with diabetes within one year after surgery. Conclusions: In patients without known diabetes, pre-operative glucose is a significant marker for post-operative complications even at moderate levels of hyperglycemia. Some of these patients likely had pre-diabetes or unrecognized diabetes at the time of surgery. Future studies are needed to determine whether such screening and follow-up of pre-operative hyperglycemia in all patients would be effective in lowering complication rates.