Clinical and Metabolic Effects of Preoperative Carbohydrate Loading Before Colorectal Surgery: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND & AIMS: To evaluate the effects of abbreviated preoperative fasting using carbohydrate-containing beverages compared with traditional fasting or placebo in patients undergoing colorectal surgery, expanding upon prior meta-analyses with an updated and more comprehensive evidence base.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were systematically searched for randomized controlled trials (RCTs) comparing patients receiving preoperative carbohydrate-containing beverages with those undergoing conventional fasting or placebo. Main endpoints were plasma insulin and blood glucose levels at operating room admission and 24 h postoperatively. Secondary outcomes included length of hospital stay (LOS), time to first defecation, postoperative ileus, and patient-reported postoperative symptoms such as nausea, vomiting, anxiety, hunger, and thirst. Analyses were conducted in R software (v4.5.2) using a random-effects model, with calculation of mean difference (MD) and 95% confidence interval (CI). Certainty of evidence was assessed using the GRADE approach, and meta-regression was performed to evaluate the surgical approach as a potential moderator of outcomes.

RESULTS

Twenty trials including 1387 patients met the inclusion criteria; 49% received a preoperative oral carbohydrate-containing beverage. No significant differences were observed in plasma insulin levels at operating room admission (MD -0.19 μUI/mL; 95% CI -1.44 to 1.07; p = 0.59) or at 24 h postoperatively (MD -3.63 μUI/mL; 95% CI -10.49 to 3.23; p = 0.19). Blood glucose levels were also similar at operating room admission (MD 2.71 mg/dl; 95% CI -10.96 to 16.39; p = 0.61) and at 24 h postoperatively (MD -8.58 mg/dl; 95% CI -35.57 to 18.40; p = 0.41). LOS (MD -1.71 days; 95% CI -2.64 to -0.78; p = 0.0015) and time to first defecation (MD -0.95 days; 95% CI -1.72 to -0.19; p = 0.02) were reduced in the carbohydrate group.

CONCLUSION

Although preoperative CHO beverages did not significantly affect plasma insulin or blood glucose levels at operating room admission or 24 h postoperatively, they were associated with statistically significantly reduced LOS and earlier gastrointestinal recovery, confirmed to be independent of surgical approach by meta-regression, without increasing postoperative complications.

PROSPERO REGISTRATION NUMBER: CRD420261286419.