title: Preoperative carbohydrate loading in patients undergoing coronary artery bypass or spinal surgery.
abstract: BACKGROUND
  Surgical stress creates a state of insulin resistance which may contribute to the development of hyperglycemia and, subsequently, postoperative complications. Consumption of an oral carbohydrate supplement before surgery may improve insulin sensitivity and reduce hyperglycemia. In this trial, we investigated the effects of carbohydrate supplementation on insulin resistance in coronary artery bypass graft and spinal decompression and fusion surgical patients.
  
  
  METHODS
  Twenty-six patients undergoing coronary artery bypass graft and 12 undergoing spine surgery were randomized to receive 800 mL of an oral carbohydrate supplement the evening before and 400 mL 2 hours before surgery (CHO) or to fasting per standard hospital protocol (FAST). Baseline and postoperative measurements of insulin sensitivity were assessed using the short insulin tolerance test and homeostasis model assessment (HOMA). Interleukin-6, C-reactive protein, and free fatty acid levels were determined at baseline, postoperatively, and 24, 48, and 72 hours after surgery. Adiponectin was measured at baseline. Subjective feelings of well-being were measured immediately before surgery, and intra- and postoperative outcomes were documented.
  
  
  RESULTS
  Postoperative insulin sensitivity did not differ significantly between the FAST and CHO groups whether measured by the short insulin tolerance test (rate of disappearance of blood glucose: 0.29%/min vs 0.38%/min; 99% confidence interval [CI] for difference, -0.17 to 0.32, P = 0.41) or HOMA (insulin resistance at values >1: 2.3 vs 3.3; 99% CI for difference, -0.8 to 2.8, P = 0.14). Circulating blood glucose levels after surgery in the CHO group, 6.2 mmol/L, tended to be lower than the FAST group, 6.9 mmol/L (99% CI for difference, -1.7 to 0.25, P = 0.05) and postoperative β-cell function, measured by HOMA-β (impaired β-cell function at values <100%), tended to be higher in the CHO group, 87%, vs 47.5% in the FAST group (99% CI for difference, -9.4 to 88.4), but these differences were not significant. Adiponectin levels were not different between groups at baseline, and levels of free fatty acid, interleukin-6 and C-reactive protein were not affected by treatment.
  
  
  CONCLUSIONS
  Preoperative carbohydrate loading did not improve postoperative insulin sensitivity. However, the observed postoperative blood glucose levels and β-cell function as well as secondary outcomes warrant further study to reevaluate traditional fasting practices in surgical patients.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Susan
authors.initials: S
authors.lastname: Tran
authors.forename: Thomas M S
authors.initials: TM
authors.lastname: Wolever
authors.forename: Lee E
authors.initials: LE
authors.lastname: Errett
authors.forename: Henry
authors.initials: H
authors.lastname: Ahn
authors.forename: C David
authors.initials: CD
authors.lastname: Mazer
authors.forename: Mary
authors.initials: M
authors.lastname: Keith
mesh_terms: D052242:Adiponectin / Q000097:blood; D000284:Administration, Oral; D000368:Aged; D000704:Analysis of Variance; D001628:Beverages; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D001026:Coronary Artery Bypass / Q000009:adverse effects; D019299:Decompression, Surgical / Q000009:adverse effects; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000097:blood; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control; D011300:Preoperative Care / Q000379:methods*; D013123:Spinal Fusion / Q000009:adverse effects; D013131:Spine / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: C499918:ADIPOQ protein, human; D052242:Adiponectin; D015415:Biomarkers; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; C508600:IL6 protein, human; D018836:Inflammation Mediators; D007328:Insulin; D015850:Interleukin-6; D002097:C-Reactive Protein