While epidemiological evidence suggests a link between diabetes mellitus and Alzheimer's disease, studies examining associations with Alzheimer's disease biomarkers report conflicting results. A recent meta-analysis study led by the Alzheimer Centre Limburg (Maastricht University), and published in the journal Neuroscience and Biobehavioral Reviews, examined associations between different measures of glucose metabolism and Alzheimer’s disease biomarkers. The authors analysed and combined 37 studies examining type 2 diabetes status, levels of glycated haemoglobin and fasting blood glucose as well as insulin resistance in relation to amyloid beta and tau.
They found that, while a more impaired glucose metabolism was associated with higher levels of tau (as measured in cerebrospinal fluid and via PET scans), this was not the case for amyloid-beta. The authors concluded that diabetes mellitus may be associated with dementia via a different pathway than amyloid-beta. The full open-access article can be read here:
https://www.sciencedirect.com/science/article/pii/S0149763424000733?via%3Dihub