Structural and functional brain abnormal alteration in patients with type 2 diabetes mellitus: A coordinate-based meta-analysis

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a prevalent chronic condition associated with a range of abnormalities in both the functional and structural aspects of the brain. However, existing studies have produced inconsistent results due to disease heterogeneity and small sample size. Therefore, we aim to examine common functional and structural alterations in patients with T2DM. METHOD: We searched PubMed, Web of Science, and Embase (published before July 2023) and included a total of 52 valid studies (58 datasets), which have 2160 patients with T2DM and 2124 healthy controls (HCs). Then, we used the anisotropic effect size seed-based d mapping (AES-SDM) to examine changes in neural activity and grey matter volume (GMV) in patients with T2DM. To validate the findings of the AES-SDM results, two additional meta-analyses were performed using activation likelihood estimation (ALE) and multilevel kernel density analysis (MKDA). RESULTS: The results showed that patients with T2DM exhibited abnormal neural activity, functional connectivity of default mode network, and GMV in brain regions related to visual processing, such as the occipital lobe, lingual gyrus, and Heschl's gyrus. In addition, functional or structural alterations were also found in other sensory-motor, cognitive, and attention-related brain regions in patients with T2DM. The results of ALE and MKDA fundamentally confirmed the findings of the AES-SDM analysis. CONCLUSION: These findings offer robust neural markers and deepen our understanding of the neurobiological underpinnings of T2DM.