Perioperative Glucose Control in the Gastric Bypass Population: How Well Do We Do, How Well Do We Think We Do, and is it Predictable

Abstract

Background: Bariatric patients are prone to insulin resistance and Postoperative Hyperglycemia (PH), which adversely affects postoperative care. Clinicians may underestimate PH on surgical wards. We aimed to characterize inpatient Blood Glucose (BG) control and identify predictors of PH after RYGB. Methods: From a single University-based center, a retrospective review of 431 patients undergoing RYGB was performed. Postoperative inpatient BG control and diabetic therapy were characterized. Attending bariatric surgeons and surgical house staff were surveyed regarding inpatient BG management. BG management was compared, and predictors of PH were identified. Results: PH (BG>180 mg/dL) was common particularly in patients with HbA1C>6.5%. From the observed sample, the mean postoperative BG was 133.5 ± 2.6 mg/dL, 167.0 ± 6.0 mg/dL, and 190.9 ± 9.2 mg/dL for each increasing HbA1c class, while physician perceived mean postoperative BG was 116.5 ± 7.9 mg/dL (p<0.002), 145.0 ± 9.3 mg/ dL (p<0.003), and 182.8 ± 14.5 mg/dL (p=ns) respectively. However, physicians overestimated the incidence of PH. Postoperative hypoglycemia was rare and also overestimated by clinicians. Four independent predictors of PH were identified, including preoperative HbA1c, preoperative nonfasting BG, a laparoscopic procedure, and preoperative diabetes. PH (mean BG>180 mg/dL) was predicted with a sensitivity of 42%, a specificity of 95%, a PPV of 60%, NPV of 90% and an overall accuracy of 87%. Conclusions: The incidence of PH is common after RYGB and may be overestimated, while mean postoperative BG may be underestimated. Postoperative hypoglycemia is rare and overestimated. Preoperative HbA1c and nonfasting BG help identify patients at greatest risk PH.