Retrieval strategy

We searched PubMed, Embase, the Web of Science, Wan-Fang database (WF), and China National Knowledge Infrastructure (CNKI) for the search. The included studies were published from the base of each database until April 4, 2022. The topic search employed combined medical topic title terminology with free-text terminology. The search terms included the following: “blood glucose”, “insulin”, “insulin sensitivity”, “insulin resistance”, “memory”, “dementia”, and “Alzheimer’s disease”. Table 1 shows the specific search process adopted for PubMed. In addition, we manually searched for references from the literature.

The specific retrieval process of PubMed

*#4 NOT #5 means that the documents retrieved in strategy #5 were excluded from the documents retrieved in strategy #4. #3 NOT #6 means only human studies were collected.