Postoperative delirium is a common and serious complication in surgical patients, often leading to prolonged hospitalisation and increased morbidity. Intranasal insulin has shown promising results in preventing postoperative delirium and protecting cognitive function. However, its use has not been standardised and is not part of treatment protocols. We performed a systematic review and meta-analysis on the effect of intranasal insulin in reducing postoperative delirium.

PubMed, EMBASE, Cochrane Central, and Web of Science databases were searched from inception to October 2025 for randomised controlled trials investigating intranasal insulin for postoperative delirium prevention in patients undergoing surgery. Risk ratios with 95% confidence intervals were computed using a random-effects model. Heterogeneity was assessed with I² statistics. We performed subgroup analyses of orthopaedics, gastrointestinal, and cardiac surgeries.

A total of 1039 patients from nine randomised controlled trials were included, of whom 574 (55.2%) received treatment with intranasal insulin. The overall incidence of delirium was significantly lower in patients treated with intranasal insulin (risk ratio = 0.36; 95% confidence interval = 0.28–0.46; p < 0.001). Subgroup analyses also demonstrated significant reductions in delirium following orthopaedic surgeries (p < 0.001), gastrointestinal surgeries (p < 0.001), and cardiac surgeries (p = 0.013).

Perioperative intranasal insulin significantly reduced the incidence of postoperative delirium in patients undergoing surgery.