Effects of preoperative carbohydrate loading on glucose metabolism and gastric contents in patients undergoing moderate surgery: a randomized, controlled trial

Nutrition. 2008 Mar;24(3):212-6. doi: 10.1016/j.nut.2007.11.003. Epub 2007 Dec 21.


Objective: Despite contrary evidence, the practice of overnight fasting before elective surgery maintains its place in tradition. However, prolonged starvation, by its catabolic action, may increase the detrimental effects of surgery. In this study, we evaluated the effects of preoperative carbohydrate loading on the gastric contents of patients and perioperative metabolism.

Methods: Seventy patients scheduled for cholecystectomy or thyroidectomy randomly were assigned to the treatment or control group. Patients in the treatment group (n = 34) received 800 mL of a carbohydrate-rich fluid on the evening before surgery and 400 mL of the same fluid 2 h preoperatively. Conversely, control patients (n = 36) underwent overnight fasting. Plasma glucose and serum insulin levels were obtained across the perioperative period and during anesthesia induction. The volume and pH of preoperative residual gastric contents also were measured.

Results: Preoperative plasma glucose levels were found to remain significantly higher in patients who had received the carbohydrate-rich fluid. Serum insulin levels that were elevated initially in the study group returned to control levels by the time of anesthesia induction. There was no statistical difference between the two groups with respect to gastric residue contents or gastric fluid pH.

Conclusion: The preoperative intake of carbohydrate-rich fluids does not appear to alter the amount or pH of gastric contents, suggesting that this is a safe procedure, in terms of aspiration risk. Furthermore, the intake of such fluid might prevent energy malnutrition.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Adult
  • Blood Glucose / metabolism*
  • Cholecystectomy
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / metabolism
  • Drinking
  • Elective Surgical Procedures
  • Fasting*
  • Female
  • Gastric Acid / chemistry
  • Gastrointestinal Contents / chemistry
  • Humans
  • Hydrogen-Ion Concentration
  • Insulin / blood*
  • Male
  • Middle Aged
  • Pneumonia, Aspiration / prevention & control
  • Preoperative Care / methods*
  • Preoperative Care / standards
  • Prospective Studies
  • Thyroidectomy


  • Blood Glucose
  • Dietary Carbohydrates
  • Insulin