Preoperative oral carbohydrate administration in adult elective surgery: protocol heterogeneity, regional practice patterns and evidence gaps-a scoping review.

TL;DR

A scoping review of 82 studies finds preoperative oral carbohydrate administration is widely studied and feasible as part of surgical recovery protocols, but the evidence base suffers from protocol inconsistency, publication bias toward Asia, and a lack of long-term outcomes in high-risk populations.

What the Study Found

Researchers conducted a systematic mapping of the literature on preoperative oral carbohydrate intake in adult elective surgery patients, examining publication trends, regional patterns, intervention protocols, and outcome domains. The review included 76 randomized controlled trials and 6 non-randomized studies published between 2015 and September 2025. A striking pattern emerged: most studies originated in China and other Asian settings, with more than two-thirds published after 2020, suggesting this is an area of intense but geographically concentrated research interest.

The most common protocol involved 200-400 mL of a carbohydrate-containing clear fluid given 2-3 hours before surgery. However, this surface consistency masks substantial variability. Across the 82 studies, formulations differed, doses varied, timing windows shifted, and control conditions diverged significantly. This heterogeneity makes cross-study comparison difficult and limits how confidently we can generalize findings. It also raises a practical question: if you're considering this intervention before surgery, you'd likely receive a different protocol depending on which hospital and which country you're in.

The measured outcomes clustered into five categories: metabolic responses (blood glucose and insulin levels), patient comfort (thirst, hunger, anxiety), inflammatory or stress markers (cortisol, IL-6, other cytokines), clinical recovery (nausea, vomiting, hospital stay duration), and safety. Most included studies reported favorable findings in metabolic or comfort domains. However, the evidence base showed critical limitations. Nearly all trials were single-center studies, outcomes focused on short-term recovery (typically in-hospital or first few days post-op), and participants were predominantly low-risk elective surgical patients. Notably absent: robust data from older adults, frail individuals, or patients with diabetes or other comorbidities who commonly undergo surgery and face higher perioperative risk.

The authors emphasize that while preoperative oral carbohydrate administration appears feasible and fits logically within Enhanced Recovery After Surgery (ERAS) pathways, the current evidence base is not as solid as the publication volume might suggest. The landscape resembles a map with dense clustering in certain regions but blank spaces elsewhere. Future research needs standardized protocols, multicenter designs, longer follow-up windows, and inclusion of populations that actually bear the highest surgical risk.

What This Means for You

If you are having elective surgery and your surgical team recommends a preoperative carbohydrate drink, the research suggests this is a reasonable and low-risk intervention that may help with blood glucose stability, patient comfort, and potentially recovery markers. The typical protocol is straightforward: a small volume of a sugar-containing clear fluid a few hours before surgery.

However, several caveats apply. First, the evidence remains concentrated in younger, healthier surgical patients without major comorbidities. If you are older, have diabetes, significant frailty, or multiple chronic conditions, the applicability of these studies to your situation is less certain. Second, most research has measured short-term outcomes (immediate recovery, hospital stay length). Long-term functional recovery, quality of life at 3-6 months post-op, or return to normal activity have rarely been assessed. Third, the wide variation in protocols means the specific drink formulation, volume, and timing used at your hospital may differ from those in any given study you read.

The practical takeaway: discuss preoperative carbohydrate drinks with your surgical team. They may already offer this as part of your ERAS protocol. If they do, the evidence suggests it is safe and potentially beneficial for comfort and metabolic stability. If you have significant comorbidities, ask how the recommendation is individualized for your risk profile. And ask about what the actual protocol is at your facility, since the details matter and vary widely in practice.

Study Details

Sources

Arksey, H., & O'Malley, L. (2005). Scoping studies: towards a methodological framework. International Journal of Social Research Methodology, 8(1), 19-32.

Enhanced Recovery After Surgery (ERAS) Society. (n.d.). ERAS protocols and guidelines. Retrieved from https://erassociety.org/

PubMed search: https://pubmed.ncbi.nlm.nih.gov/42798524/

Disclosure: This article summarizes a scoping review mapping trends in published evidence rather than reporting new primary research data. The conclusions reflect the authors' assessment of heterogeneity and evidence gaps, not a definitive clinical recommendation. Consult your surgical team about preoperative protocols tailored to your individual clinical situation.