BACKGROUND & AIMS: The effectiveness of preoperative carbohydrate loading(PCL) on postoperative insulin resistance(IR) is controversial. In addition, the effect of different doses of carbohydrates on postoperative IR is also controversial. Therefore, this study aimed to investigate the efficiency of PCL on postoperative IR and the optimal regimen for the effect on postoperative IR. METHODS: A systematic search of clinical randomized controlled trials was performed to extract basic information about the included studies, specific regimens of PCL, and preoperative and postoperative IR. Network meta-analysis was performed using frequentist random effects. A total of 7 regimens were identified by categorizing them based on frequency, timing, control groups, and conducting subgroup analysis according to surgical procedure. High (>
45 g) and low (≤45 g) doses were divided according to the standard definition of PCL. Dose analysis was performed on studies in the subgroups that met the optimal frequency and timing regimen. Reporting of results based on weighted mean differences(WMD), 95 % confidence intervals(95%CrI), and the surface under the cumulative ranking(SUCRA). RESULTS: Carbohydrate loading given only 3 h before surgery is more strongly associated with insulin resistance than fasting(WMD: -4.04,95%CrI: -5.67 to -2.40) and placebo(WMD: -4.00,95%CrI: -5.98 to -2.02). Single-dose preoperative 3 h regimen has the highest probability of being the optimal regimen(SUCRA = 90.9 %). This is also true in open(SUCRA = 93.7 %) and laparoscopic surgery(SUCRA = 99.9 %). Analyzed using a fixed-effects model in open and laparoscopic surgery. In open surgery, high-dose and low-dose carbohydrates are associated with postoperative IR compared with fasting(high-dose: WMD: -1.75,95%CrI: -1.95 to -1.54
low-dose: WMD: -2.46,95%CrI: -3.70 to -1.23) and placebo(high-dose: WMD: -5.37,95%CrI: -6.99 to -3.76
low-dose: WMD: -6.09,95%CrI: -7.29 to -4.90). Low-dose carbohydrates(SUCRA = 95.3 %) have the highest probability of being the best option. In laparoscopic surgery, high-dose and low-dose carbohydrates are also associated with postoperative IR compared with fasting(high-dose (WMD: -5.70,95 %, CrI: -7.63 to -3.77)
low-dose (WMD: -3.69,95%CrI: -4.11 to -3.27))and placebo(high-dose (WMD: -5.73,95%CrI: -7.72 to -3.74)
low-dose (WMD: -3.72,95%CrI: -4.14 to -3.30)). SUCRA for high-dose carbohydrates is 99.2 %. CONCLUSION: Preoperative implementation of carbohydrate loading is more beneficial in alleviating postoperative insulin resistance than fasting and placebo. Conducting PCL on the morning of surgery is more effective in relieving postoperative IR. For both open and laparoscopic surgeries, administering carbohydrate loading 3 h before the surgery may represent the optimal regimen. Further studies are needed to investigate the effect of different doses on postoperative IR.