Preoperative carbohydrate loading before colorectal surgery: a systematic review and meta-analysis of randomized controlled trials

Purpose Preoperative carbohydrate loading has been introduced as a component of many enhanced recovery after surgery programs. Evaluation of current evidence for preoperative carbohydrate loading in colorectal surgery has never been synthesized. Methods MEDLINE, Embase, and CENTRAL were searched until May 2021. Randomized controlled trials (RCTs) comparing patients undergoing colorectal surgery with and without preoperative carbohydrate loading were included. Primary outcomes were changes in blood insulin and glucose levels. A pairwise meta-analysis was performed using inverse variance random effects. Results The search yielded 3656 citations, from which 12 RCTs were included. In total, 387 patients given preoperative carbohydrate loading (47.2% female, age: 62.0 years) and 371 patients in control groups (49.4% female, age: 61.1 years) were included. There was no statistical difference for blood glucose and insulin levels between both patient groups. Patients receiving preoperative carbohydrate loading experienced a shorter time to first flatus (SMD: − 0.48 days, 95% CI: − 0.84 to − 0.12, p = 0.008) and stool (SMD: − 0.50 days, 95% CI: − 0.86 to − 0.14, p = 0.007). Additionally, length of stay was shorter in the preoperative carbohydrate loading group (SMD: − 0.51 days, 95% CI: − 0.88 to − 0.14, p = 0.007). There was no difference in postoperative morbidity and patient well-being between both groups. Conclusions Preoperative carbohydrate loading does not significantly impact postoperative glycemic control in patients undergoing colorectal surgery; however, it may be associated with a shorter length of stay and faster return of bowel function. It merits consideration for inclusion within colorectal enhanced recovery after surgery protocols.