Background <p>Mechanistic and cross-sectional studies have indicated a correlation between insulin resistance and dementia; however, further evidence from prospective studies is needed to elucidate the relationship between insulin resistance and the risk of developing dementia.</p> Methods <p>A systematic review and meta-analysis were conducted. Searches were performed in PubMed, EMBASE, and the Cochrane Library for relevant articles published up to December 20th, 2025. Cohort studies investigating the risk of dementia onset associated with insulin resistance were included.</p> Results <p>A total of ten studies were included in the meta-analysis. Insulin resistance was associated with an increased risk of all-cause dementia (HR = 1.11, 95% CI 1.03–1.21, 9 studies included) and Alzheimer’s disease (HR = 1.23, 95% CI 1.01–1.50, 7 studies included). A similar association was observed between insulin resistance and the risk of vascular dementia (HR = 1.04, 95% CI 1.01–1.07, 4 studies included).</p> Conclusion <p>The available evidence suggested that insulin resistance might be associated with an increased risk of all-cause dementia, Alzheimer’s disease, and vascular dementia. Further well-designed prospective studies are warranted to clarify the causal relationship between insulin resistance and dementia.</p> Trial registration <p>The study was registered with PROSPERO under the registration number CRD42024550842 on June 5th, 2024.</p>