When logistic regression analyses were performed separately for the DM subjects with dementia and DM subjects without dementia, the results showed that metformin use history reduced risk of delirium both in non-dementia group (OR: 0.54, 95%CI: 0.32–0.91, p = 0.02) (Supplementary Table 1) and dementia group (OR: 0.40, 95%CI: 0.13–1.21, p = 0.11) (Supplementary Table 2) after controlling for age, sex, CCI, BMI, and history of insulin use, although dementia group did not reach statistically significant level likely due to reduced sample size. Here, INS is linked to delirium.