INS and delirium: A clinical study on POD in patients undergoing laparoscopic radical surgery for gastrointestinal malignancies showed that 20 units of intranasal insulin administered for 2 days before surgery (5 times in total) significantly reduced delirium (12.5% in the insulin group vs. 47.5% in the placebo group) and suppressed systemic inflammation during the 5 days after surgery [33].